WorldWideScience
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Analysis of environmental issues related to small-scale hydroelectric development. III. Water level fluctuation  

Energy Technology Data Exchange (ETDEWEB)

Potential environmental impacts in reservoirs and downstream river reaches below dams that may be caused by the water level fluctuation resulting from development and operation of small scale (under 25MW) hydroelectric projects are identified. The impacts discussed will be of potential concern at only those small-scale hydroelectric projects that are operated in a store and release (peaking) mode. Potential impacts on physical and chemical characteristics in reservoirs resulting from water level fluctuation include resuspension and redistribution of bank and bed sediment; leaching of soluble organic matter from sediment in the littoral zone; and changes in water quality resulting from changes in sediment and nutrient trap efficiency. Potential impacts on reservoir biota as a result of water level fluctuation include habitat destruction and the resulting partial or total loss of aquatic species; changes in habitat quality, which result in reduced standing crop and production of aquatic biota; and possible shifts in species diversity. The potential physical effects of water level fluctuation on downstream systems below dams are streambed and bank erosion and water quality problems related to resuspension and redistribution of these materials. Potential biological impacts of water level fluctuation on downstream systems below dams result from changes in current velocity, habitat reduction, and alteration in food supply. These alterations, either singly or in combination, can adversely affect aquatic populations below dams. The nature and potential significance of adverse impacts resulting from water level fluctuation are discussed. Recommendations for site-specific evaluation of water level fluctuation at small-scale hydroelectric projects are presented.

Hildebrand, S.G. (ed.)

1980-10-01

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Preliminary assessment of the impact of fluctuating water levels on northern pike in Reindeer Lake  

International Nuclear Information System (INIS)

Reindeer Lake in north eastern Saskatchewan regulates water levels for the Island Falls hydroelectric power plant. Since inception of the Whitesand Dam on the lake, there have been concerns that fluctuating water levels could be adversely impacting the habitat and population of northern pike in the lake. The extent of water level fluctuations during the pike spawning period of Reindeer Lake and its effect on spawning success was investigated. Since construction of the Whitesand Dam in 1942 Reindeer Lake water levels have averaged ca 1.71 m higher than had the dam not existed, creating ca 430 km2 of new surface area. Much of this area is shallow water and prone to growth of aquatic vegetation, which is suitable spawning and nursery habitat for northern pike. Annual and periodic water level fluctuations of Reindeer Lake have been higher than under natural conditions. During northern pike spawning and nursing periods, water levels in the lake have generally increased, in 60 out of 64 y. It is concluded that operation of the dam has not caused any direct negative impacts on the northern pike habitat in the lake. 2 refs., 4 figs., 4 tabs

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Water-level fluctuations, emersion regimes, and variations of echinoid populations on a Caribbean reef flat  

Science.gov (United States)

This paper examines fluctuations in water level over a Caribbean reef flat at Punta Galeta, Panamá. In an analysis of approximately ten years of records, the mean diurnal range of the tides was 24·5 cm and varied Echinometra lucunter and E. viridis did not exhibit reductions in abundance that were synchronous with the seasonal exposures of the reef flat.

Cubit, John D.; Windsor, Donald M.; Thompson, Ricardo C.; Burgett, Jeff M.

1986-06-01

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Fuzzy logic model of lake water level fluctuations in Lake Van, Turkey  

Science.gov (United States)

Lake Van is one of the largest terminal lakes in the world. In recent years, significant lake level fluctuations have occurred and can be related to global climatic change. This fluctuation sometimes exhibits abrupt shifts. Floods originating from the lake can cause considerable damage and loss in agriculture and urban areas. Therefore, water level forecasting plays a significant role in planning and design. This study is aimed at predicting future lake levels from past rainfall amounts and water level records. A dynamical change of the lake level is evaluated by the fuzzy approach. The fuzzy inference system has the ability to use fuzzy membership functions that include the uncertainties of the concerned event. This method is applied for Lake Van, in east Turkey. Furthermore, model capabilities are compared with ARMAX model. It is shown that lower absolute errors are obtained with the Takagi-Sugeno fuzzy approach than with the ARMAX model.

Altunkaynak, A.; ?en, Z.

2007-11-01

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Earthquake-induced water-level fluctuations at Yucca Mountain, Nevada, June 1992  

International Nuclear Information System (INIS)

This report presents earthquake-induced water-level and fluid-pressure data for wells in the Yucca Mountain area, Nevada, during June 1992. Three earthquakes occurred which caused significant water-level and fluid-pressure responses in wells. Wells USW H-5 and USW H-6 are continuously monitored to detect short-term responses caused by earthquakes. Two wells, monitored hourly, had significant, longer-term responses in water level following the earthquakes. On June 28, 1992, a 7.5-magnitude earthquake occurred near Landers, California causing an estimated maximum water-level change of 90 centimeters in well USW H-5. Three hours later a 6.6-magnitude earthquake occurred near Big Bear Lake, California; the maximum water-level fluctuation was 20 centimeters in well USW H-5. A 5.6-magnitude earthquake occurred at Little Skull Mountain, Nevada, on June 29, approximately 23 kilometers from Yucca Mountain. The maximum estimated short-term water-level fluctuation from the Little Skull Mountain earthquake was 40 centimeters in well USW H-5. The water level in well UE-25p number-sign 1, monitored hourly, decreased approximately 50 centimeters over 3 days following the Little Skull Mountain earthquake. The water level in UE-25p number-sign 1 returned to pre-earthquake levels in approximately 6 months. The water level in the lower interval of well USW H-3 increased 28 centimeters following the Little Skull Mountain earthquake. The Landers and Little Skull Mountain earthquakes caused responses in 17 intervals of 14 hourly monitored wells, however, most responses were small and of short duration. For several days following the major earthquakes, many smaller magnitude aftershocks occurred causing measurable responses in the continuously monitored wells

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Establishment of earth tides effect on water level fluctuations in an unconfined hard rock aquifer using spectral analysis  

CERN Document Server

Short-interval water level measurements using automatic water level recorder in a deep well in an unconfined crystalline rock aquifer at the campus of NGRI, near Hyderabad shows a cyclic fluctuation in the water levels. The observed values clearly show the principal trend due to rainfall recharge. Spectral analysis was carried out to evaluate correlation of the cyclic fluctuation to the synthetic earth tides as well as groundwater withdrawal time series in the surrounding. It was found that these fluctuations have considerably high correlation with earth tides whereas groundwater pumping does not show any significant correlation with water table fluctuations. It is concluded that earth tides cause the fluctuation in the water table. These fluctuations were hitherto unobserved during manual observations made over larger time intervals. It indicates that the unconfined aquifer is characterised by a low porosity.

Maréchal, Jean-Christophe; Ahmed, Shakeel; Lachassagne, Patrick

2010-01-01

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Effects of Barometric Fluctuations on Well Water-Level Measurements and Aquifer Test Data  

Energy Technology Data Exchange (ETDEWEB)

The Pacific Northwest National Laboratory, as part of the Hanford Groundwater Monitoring Project, examines the potential for offsite migration of contamination within underlying aquifer systems. Well water-level elevation measurements from selected wells within these aquifer systems commonly form the basis for delineating groundwater-flow patterns (i.e., flow direction and hydraulic gradient). In addition, the analysis of water-level responses obtained in wells during hydrologic tests provides estimates of hydraulic properties that are important for evaluating groundwater-flow velocity and transport characteristics. Barometric pressure fluctuations, however, can have a discernible impact on well water-level measurements. These barometric effects may lead to erroneous indications of hydraulic head within the aquifer. Total hydraulic head (i.e., sum of the water-table elevation and the atmospheric pressure at the water-table surface) within the aquifer, not well water-level elevation, is the hydrologic parameter for determining groundwater-flow direction and hydraulic gradient conditions. Temporal variations in barometric pressure may also adversely affect well water-level responses obtained during hydrologic tests. If significant, adjustments or removal of these barometric effects from the test-response record may be required for quantitative hydraulic property determination. This report examines the effects of barometric fluctuations on well water-level measurements and evaluates adjustment and removal methods for determining areal aquifer head conditions and aquifer test analysis. Two examples of Hanford Site unconfined aquifer tests are examined that demonstrate barometric response analysis and illustrate the predictive/removal capabilities of various methods for well water-level and aquifer total head values. Good predictive/removal characteristics were demonstrated with best corrective results provided by multiple-regression deconvolution methods.

FA Spane, Jr.

1999-12-16

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Earthquake-induced water-level fluctuations at Yucca Mountain, Nevada, April 1992  

International Nuclear Information System (INIS)

This report presents earthquake-induced water-level and fluid- pressure data for well USW H-5 during April 1992. Well USW H-5 is located in the Yucca Mountain area, Nevada. On April 22,1992 a 6.2-magnitude earthquake occurred in southern California which caused a maximum fluid-pressure change of approximately 50 centimeters in well USW H-5. Within 18 hours on April 25--26, 1992, three major earthquakes occurred in northern California. The water-level responses to these earthquakes were detected in well USW H-5. The maximum water-level fluctuation from the northern California earthquakes was in excess of 52.5 cm

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A Hydro-Economic Model for Water Level Fluctuations: Combining Limnology with Economics for Sustainable Development of Hydropower  

Science.gov (United States)

Water level fluctuations in lakes lead to shoreline displacement. The seasonality of flooding or beaching of the littoral area affects nutrient cycling, redox gradients in sediments, and life cycles of aquatic organisms. Despite the ecological importance of water level fluctuations, we still lack a method that assesses water levels in the context of hydropower operations. Water levels in reservoirs are influenced by the operator of a hydropower plant, who discharges water through the turbines or stores water in the reservoir, in a fashion that maximizes profit. This rationale governs the seasonal operation scheme and hence determines the water levels within the boundaries of the reservoir's water balance. For progress towards a sustainable development of hydropower, the benefits of this form of electricity generation have to be weighed against the possible detrimental effects of the anthropogenic water level fluctuations. We developed a hydro-economic model that combines an economic optimization function with hydrological estimators of the water balance of a reservoir. Applying this model allowed us to accurately predict water level fluctuations in a reservoir. The hydro-economic model also allowed for scenario calculation of how water levels change with climate change scenarios and with a change in operating scheme of the reservoir (increase in turbine capacity). Further model development will enable the consideration of a variety of additional parameters, such as water withdrawal for irrigation, drinking water supply, or altered energy policies. This advances our ability to sustainably manage water resources that must meet both economic and environmental demands. PMID:25526619

Hirsch, Philipp Emanuel; Schillinger, Sebastian; Weigt, Hannes; Burkhardt-Holm, Patricia

2014-01-01

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Effect and propagation of water level fluctuations in a sloping sandy beach -- Unsaturated porous media II: numerical simulation test of single harmonic wave (long run)  

OpenAIRE

In coastal processes, the strong water movements due to short periodic waves (such as sea swell) can induce irregular water level fluctuations in the swash zone and within the sandy beach. The measured water level fluctuations with very complex entry water level fluctuations in a wave canal with a sloping sandy beach were analyzed by using 7 capacitive sensors. Numerical simulations have also been implemented in order to complement the experimental water level signal...

Wang, Yunli; Ababou, Rachid; Marcoux, Manuel

2012-01-01

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Effects of Microscale Water Level Fluctuations and Altered Ultraviolet Radiation on Periphytic Microbiota.  

Science.gov (United States)

Abstract Microscale fluctuations in water level (1-20 mm) are common on a diurnal basis in shallow (evapotranspiration losses during the daytime in excess of groundwater resupply. These depth variations alter the intensity of UV irradiance reaching attached periphytic algal and bacterial microbial communities. Effects of alterations of UV irradiance by micro-changes in water level on periphytic microbiota were examined experimentally. Attached microbial communities, grown on glass fiber filters in situ in a natural wetland, were exposed experimentally to near-natural levels of UV irradiance of differing spectral quality. UV intensity was altered by varying the distance of the communities from the light source, changes in UV-attenuating natural dissolved organic matter (DOM), and small changes in water level (2 or 4 mm). Algal productivity and photosynthetic oxygen production were significantly reduced by small enhancements of UV-B radiation, by decreased water levels of only 2 mm, and by reductions in concentrations of DOM. UV-B had only small short-term effects on chlorophyll a, although small increases in water depth and DOM concentration reduced pigment damage. Experimental removal of UV-B during in situ growth indicated that algae could adapt to UV radiation during growth in natural environments. Microbial oxygen consumption and bacterial productivity and biomass were also lowered significantly by UV-B exposure, and damage decreased with small (2 mm) increases in water depth or in DOM concentration. Selective inhibitors of algal photosynthesis and production of released extracellular organic substrates caused a concomitant reduction in bacterial productivity and a significant increase in magnitude of UV-B damage to bacterial biomass. These effects suggested that metabolic interactions between the periphytic autotrophs and heterotrophs altered community responses to UV-B radiation. Microscale water level reductions, common on a diurnal basis in shallow wetlands, and associated increased UV intensity can result in rapid alterations in periphytic metabolism.http://link.springer-ny.com/link/service/journals/00248/bibs/38n3p253.html

Kahn; Wetzel

1999-10-01

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Revegetation Strategies for Water-Level Fluctuation Zone of the Three Gorges Reservoir Region  

Directory of Open Access Journals (Sweden)

Full Text Available After the full functioning of the Three Gorges Dam (TGD, the hydrologic regime will be markedly changed and most of the pre-dam vegetation in the new Water-Level Fluctuation Zone (WLFZ may fail to persist. How to revegetate WLFZ of the Three Gorges Reservoir Region (TGRR has become a hot topic for the scientific community and the governments. Based on review of scientific literature and the findings of our research, we here bring forward a scheme addressing strategies for revegetation of WLFZ of TGRR. Firstly, monitor vegetation dynamics based on permanent plots along the Three Gorges upstream from TGD, potentially providing suitable plants for the future revegetation plans. Secondly, examine the potential of soil seed bank for revegetation of the above-ground vegetation, and evaluate self-regeneration of the post-dam vegetation. Based on these data, select suitable plants for revegetation that integrate desirable physiological and life-history traits.Specifically, wetland vegetation could be constructed with lotus (Nelumbo nucifera and aquatic plants. For sites with gentle terrain and fairly hospitable soil conditions, vertical planting of trees, shrubs and grasses / forbs along the elevation gradient could be considered. To attain the sustainable vegetation cover, the newly artificial vegetation should be monitored for at least 5 years.

JIANG Ming-xi

2012-05-01

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Effects of fluctuations in river water level on virus removal by bank filtration and aquifer passage — A scenario analysis  

Science.gov (United States)

Riverbank filtration is an effective process for removing pathogenic viruses from river water. Despite indications that changing hydraulic conditions during floods can affect the efficacy of riverbank filtration to remove viruses, the impact on advection and dispersion of viruses in the riverbank is not well understood. We investigated the effects of fluctuations in river water level on virus transport during riverbank filtration, considering 3-D transient groundwater flow and virus transport. Using constant removal rates from published field experiments with bacteriophages, removal of viruses with distance from the riverbank was simulated for coarse gravel, fine gravel and fine sandy gravel. Our simulations showed that, in comparison with steady flow conditions, fluctuations in river water level cause viruses to be transported further at higher concentrations into the riverbank. A 1-5 m increase in river water levels led to a 2- to 4-log (log10 reduction in concentration relative to the initial concentration in the river) increase in virus concentration and to up to 30 % shorter travel times. For particular cases during the receding flood, changing groundwater flow conditions caused that pristine groundwater was carried from further inland and that simulated virus concentrations were more diluted in groundwater. Our study suggests that the adverse effect of water level fluctuations on virus transport should be considered in the simulation of safe setback distances for drinking water supplies.

Derx, J.; Blaschke, A. P.; Farnleitner, A. H.; Pang, L.; Blöschl, G.; Schijven, J. F.

2013-04-01

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Deep bore well water level fluctuations in the Koyna region, India: the presence of a low order dynamical system in a seismically active environment  

Directory of Open Access Journals (Sweden)

Full Text Available Water level fluctuations in deep bore wells in the vicinity of seismically active Koyna region in western India provides an opportunity to understand the causative mechanism underlying reservoir-triggered earthquakes. As the crustal porous rocks behave nonlinearly, their characteristics can be obtained by analysing water level fluctuations, which reflect an integrated response of the medium. A Fractal dimension is one such measure of nonlinear characteristics of porous rock as observed in water level data from the Koyna region. It is inferred in our study that a low nonlinear dynamical system with three variables can predict the water level fluctuations in bore wells.

D. V. Ramana

2009-05-01

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The best farm-level irrigation strategy changes seasonally with fluctuating water availability  

OpenAIRE

Around the globe farmers managing irrigated crops face a future with a decreased and more variable water supply. To investigate generic adaptation issues, a range of on-farm strategies were evaluated for apportioning limited water between fields and enterprises using a typical case-study farm from Australia's Riverina region. These strategies are compared for a range of seasonal water availability levels. The analysis did not address investment in new irrigation technologies or new crops, but...

Gaydon, D. S.; Meinke, H.; Rodriguez, D.

2012-01-01

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Seepage Analysis of Rock-Fill Dam Subjected to Water Level Fluctuation: A case study on Gotvand-Olya Dam  

Directory of Open Access Journals (Sweden)

Full Text Available The Gotvand-Olya Dam is a rock-fill dam, located at Khuzestan province in southwest of Iran. Since the dam is subjected to the daily water level fluctuation, such as rapid drawdown and refill, thus induce a structural impact on the behavior of dam body, it draws many soil engineering concerns. In this paper, seepage analysis of the rock-fill dam was primarily conducted to evaluate the dam safety against the leakage through the dam body. Traditionally, steady-state analysis was employed to investigate the seepage in the dam body, summing that water level is fixed at two cases: high and low water levels. Consequently, it was not able to properly reflect the time-dependent characteristics of seepage phenomena. In this study, seepage analysis was numerically performed using 2-D FEM transient analysis. As a particular boundary condition for an analysis, the water level fluctuation was incorporated to simulate the daily changes. As a result, various seepage phenomena were quantified such as hydraulic gradient, seepage vector and pore water pressure distribution at the corresponding time of interest as the water level rises and recedes. At steady state analysis, the seepage flux at high water level in downstream area was predicted to be 78 l/s. In additions, the seepage flux measured and estimated were both acceptable considering design criteria. The result of this study proves that there is no sign of hazardous sources contributing to the possibility of piping, internal erosion and excess leakage through the dam body.

Ali Beheshti

2013-01-01

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Wetland Ecohydrology: stochastic description of water level fluctuations across the soil surface  

Science.gov (United States)

Wetlands provide a suite of social and ecological critical functions such as being habitats of disease-carrying vectors, providing buffer zones against hurricanes, controlling sediment transport, filtering nutrients and contaminants, and a repository of great biological diversity. More recently, wetlands have also been recognized as crucial for carbon storage in the context of global climate change. Despite such importance, quantitative approaches to many aspects of wetlands are far from adequate. Therefore, improving our quantitative understanding of wetlands is necessary to our ability to maintain, manage, and restore these invaluable environments. In wetlands, hydrologic factors and ecosystem processes interplay and generate unique characteristics and a delicate balance between biotic and abiotic elements. The main hydrologic driver of wetland ecosystems is the position of the water level that, being above or below ground, determines the submergence or exposure of soil. When the water level is above the soil surface, soil saturation and lack of oxygen causes hypoxia, anaerobic functioning of microorganisms and anoxic stress in plants, that might lead to the death of non-adapted organisms. When the water level lies below the soil surface, the ecosystem becomes groundwater-dependent, and pedological and physiological aspects play their role in the soil water balance. We propose here a quantitative description of wetland ecohydrology, through a stochastic process-based water balance, driven by a marked compound Poisson noise representing rainfall events. The model includes processes such as rainfall infiltration, evapotranspiration, capillary rise, and the contribution of external water bodies, which are quantified in a simple yet realistic way. The semi-analytical steady-state probability distributions of water level spanning across the soil surface are validated with data from the Everglades (Florida, USA). The model and its results allow for a quantitative analysis of the long term behavior of biotic and abiotic factors which depend on the position of the water level and enable the assessment of impacts of climate changes on the wetland ecosystem.

Tamea, S.; Muneepeerakul, R.; Laio, F.; Ridolfi, L.; Rodriguez-Iturbe, I.

2009-12-01

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Properties of Adsorption-Desorption of Pb in Soil of the Water-Level-Fluctuating in Three Gorges Reservoir Region  

Directory of Open Access Journals (Sweden)

Full Text Available The soil of water-level-fluctuating adsorption and desorption characterisitics of Pb2+ ion in the Three Gorges Reservoir region are studied on pH, organic matter, ionic strength and effect of Pb2+ ion concentration. It is revealed in the law of soil adsorption and desorption of Pb2+ ion in water-level-fluctuationg of the Three Gorges reservoir region, for providing the basis on lead contamination risk assessment and forecasting, pollution control and the use of land resources. Electing purple soil of the main soil type is also studied by using simulation experiments and constant temperature oscillation balance method. With atomic absorption spectrophotometer determination of Pb2+ ion adsorption and desorption volume. The results show that:1pH value very significantyly affects the soil adsorption capacity of Pb2+ ion (ppH>organic matter > Pb2+ ion concentration, affect the Pb2+ soil desorption amount in the order of :pHwater in the Three Gorges Reservoir region, the soil of water-level-fluctuating is affected by various factors, leading to change the soil properties and affect the environmental behavior of heavy metals and way cause enviromental pollution and ecological hazards.

FANG Lu-qiu

2010-05-01

19

Water Level Fluctuations in the Congo Basin Derived from ENVISAT Satellite Altimetry  

OpenAIRE

In the Congo Basin, the elevated vulnerability of food security and the water supply implies that sustainable development strategies must incorporate the effects of climate change on hydrological regimes. However, the lack of observational hydro-climatic data over the past decades strongly limits the number of studies investigating the effects of climate change in the Congo Basin. We present the largest altimetry-based dataset of water levels ever constituted over the entire Congo Basin. This...

Mélanie Becker; Joecila Santos da Silva; Stéphane Calmant; Vivien Robinet; Laurent Linguet; Frédérique Seyler

2014-01-01

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Relationship between mercury accumulation in young-of-the-year yellow perch and water-level fluctuations.  

Science.gov (United States)

A three-year (2001-2003) monitoring effort of 14 northeastern Minnesota lakes was conducted to document relationships between water-level fluctuations and mercury bioaccumulation in young-of-the-year (YOY) yellow perch (Perca flavescens) collected in the fall of each year at fixed locations. Six of those lakes are located within or adjacent to Voyageurs National Park and are influenced by dams on the outlets of Rainy and Namakan lakes. One site on Sand Point Lake coincides with a location that has nine years of previous monitoring suitable for addressing the same issue over a longer time frame. Mean mercury concentrations in YOY yellow perch at each sampling location varied significantly from year to year. For the 12-year monitoring site on Sand Point Lake, values ranged from 38 ng gww(-1) in 1998 to 200 ng gww(-1) in 2001. For the 14-lake study, annual mean concentrations ranged by nearly a factor of 2, on average, for each lake over the three years of record. One likely factor responsible for these wide variations is that annual water-level fluctuations are strongly correlated with mercury levels in YOY perch for both data sets. PMID:16382948

Sorensen, John A; Kallemeyn, Larry W; Sydor, Michael

2005-12-01

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Evaluation of Radionuclides, Toxic Metals and Fluctuation ofRadioactivity Level in Muria Water  

International Nuclear Information System (INIS)

Study on Radionuclides, toxic metals and radioactivity level fluctuationin Water samples of Muria area have been carried out. The sampling locationwere Sepalung Tubanan, Hulu Putih, Balong, Geulis and Banjaran river, LemahAbang, Krakal and Baron coasts. Alpha, betha, and gamma radioactivity levelswere gross counted. Radionuclides identification were done by using gammaspectrometer. Pu-239/240 were analyzed by dilution and solvent extractionstep before counted by alpha spectrometer. Toxic metals were analyzed byInstrumental Neutron Activation Method, with the neutron flux of5.1010.n.cm-2.s-1. Data collection of toxic elements was carried outduring 4 years since 1996 to 1999, and 2 years for radioactivity level studysince 1998 and 1999. High concentration of Zn in Balong and Hulu Putih riverwater samples in 1999 higher than the governmental quality standard value foragriculture. The radionuclides contaminant as Pu-239/240 and Cs-137 were notdetected, and the radioactivity level and identified radionuclides were allnaturally. (author)

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Observations of Water-Level Fluctuations Induced by Local and Distant Earthquakes at Two Wells in Hualien, Eastern Taiwan  

Science.gov (United States)

Sustained water level fluctuations may occur in response to local changes of volumetric strain associated with passage of seismic waves or ground deformation. Two wells, namely HLC-05 and HLC-03, with high sampling rates (1 and 6 second) have been deployed for the purpose of monitoring the dynamic response of water level and static steps induced by earthquakes in Hualien area, eastern Taiwan since 2002. Through our observations, we have found the following results. (1) The water level changes may occur with earthquakes of magnitude M>=0.43+2.39log10(D), where D is the distance from the well; (2) the peak water level fluctuations (PWL) are apparently proportional to the peak ground velocity (PGV) and peak ground displacement (PGD) on logarithmic scales, but no clear trend with the peak ground acceleration (PGA). We performed regression to obtain the relationships between PWL and PGV, and PWL and PGD, respectively, as follows: For the HLC-05 well: ln(PWL)=0.83ln(PGVH)-3.22, ln(PWL)=0.97ln(PGVV)-2.27, ln(PWL)=0.80ln(PGDH)-1.70, ln(PWL)=0.91ln(PGDV)-0.83 For the HLC-03 well: ln(PWL)=0.73ln(PGVH)-3.29, ln(PWL)=0.73ln(PGVV)-2.65, ln(PWL)=0.53ln(PGDH)-2.44, ln(PWL)=0.57ln(PGDV)-1.93 where the subscripts H and V represent the horizontal and the vertical component, of ground motion respectively.

Liu, C.; Huang, M.; Tsai, Y.; Lee, C.

2005-12-01

23

Response of Eichhornia crassipes (Pontederiaceae) to water level fluctuations in two lakes with different connectivity in the Paraná River floodplain  

Scientific Electronic Library Online (English)

Full Text Available Se analiza la respuesta de Eichhornia crassipes, una de las plantas acuáticas más frecuentes en la planicie de inundación del río Paraná, a las fluctuaciones del río en dos lagos con diferente conectividad. Las muestras fueron tomadas en 13 condiciones hidrológicas entre Marzo de 1997 y Diciembre de [...] 2001. Durante el periodo de prolongada conectividad hidrológica, el área cubierta por el agua aumenta más de tres veces y el contenido de nitrógeno inorgánico disuelto fue mayor en comparación con la condición de prolongado aislamiento. En comparación con las plantas del lago más aislado del río, las del más conectado tuvieron significativamente menor densidad de hojas, hojas más largas, menor biomasa de raíces y menor cociente entre la biomasa de las partes aéreas y las partes sumergidas. Las diferencias en la altura y la biomasa de hojas y raíces entre diferentes condiciones hidrológicas y la no significativa relación entre el tamaño y su densidad, indican que las características morfológicas de las plantas responden a fluctuaciones del nivel del agua. Durante la prolongada conexión con el río el contenido de nutrientes de las hojas maduras fue alto, en tanto que durante el aislamiento prolongado las hojas tuvieron mayor contenido de lignina y alto cociente L:N. El éxito de Eichhornia crassipes en la ocupación de hábitats sujetos a amplias y erráticas fluctuaciones del nivel del agua parece estar relacionado con su capacidad para modificar sus características morfológicas en función de las fluctuaciones del nivel del agua. Abstract in english Floodplain lakes are especially dynamic due to the irregular flow regime of the Paraná River and its location along the geomorphologic gradient between the lakes and the river. The response of Eichhornia crassipes (Mart.) Solms (one of the most frequent aquatic plant) was studied in two floodplain l [...] akes with different flooding regimes. Samples were taken between March 1997 and December 2001 on 13 different hydrologic conditions during prolonged hydrologic connection and prolonged hydrologic isolation. Leaf height, leaf density, biomass and nutrient content of the mature leaves of E. crassipes were measured and related to water level fluctuation and the hydrologic connectivity. The lake more connected with the main channel had a long lasting inundation phase. In this condition the surface area covered by water increased more than three times compared to prolonged hydrologic isolation condition. As river water entered the floodplain lakes, dissolved inorganic nitrogen increased to high values, especially NO3-, whereas the isolation condition was characterised by a decrease in NO3- concentrations to undetectable levels. Compared to plants growing in the more isolated lake, those growing in the more connected lake had a significantly lower leaf density, longer leaves, less root biomass and lower ratio between below-ground and above-ground biomasses. However, total and leaf biomasses were not significantly different between sites. In each lake, differences in leaf height, leaf biomass and root biomass between prolonged hydrologic connection and isolation, as well as the insignificant relationship between leaf size and leaf density, indicate that the morphological traits of E. crassipes respond to pluri-annual water level fluctuations. The highest nutrient concentration in mature leaves was registered at the end of the prolonged hydrologic connection in the more connected lake. During the prolonged isolation, leaves had more lignin and a higher L:N ratio than at high waters, at the same sites. The success of E. crassipes in occupying habitats subjected to wide and erratic fluctuations in water level, such as the Paraná River floodplain, appears to be related to its ability to modify morphological traits according to water level. Rev. Biol. Trop. 56 (2): 613-623. Epub 2008 June 30.

Juan José, Neiff; Sylvina Lorena, Casco; Alicia, Poi de Neiff.

2008-06-01

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Revegetation impacts soil nitrogen dynamics in the water level fluctuation zone of the Three Gorges Reservoir, China.  

Science.gov (United States)

Revegetations in riparian ecosystem are important in regulating soil nitrogen (N) dynamics. However, impacts of revegetation on soil N cycling and thereby on ecosystem functioning are not fully understood. We conducted an in situ incubation in the water level fluctuation zone (WLFZ) of the Three Gorges Reservoir region to evaluate soil N transformation including net N mineralization rate, net ammonification rate, net nitrification rate, net denitrification rate, N leaching and plant N uptake as well as the soil inorganic N (NH4(+)-N and NO3(-)-N) concentration in the top soils (0-20cm) following revegetations (implementing tree, shrub and herb plantations) over two years. The soil inorganic N concentration and N leaching were lower in the tree soils than in herb and shrub soils. Tree plantations decreased net N mineralization rate and net ammonification rate compared to herb and shrub soils, possibly due to lower soil organic carbon (SOC) input and soil temperatures. Whereas tree plantations increased soil net denitrification rate compared to herb and shrub soils because of higher tree NO3(-)-N uptake together with higher net nitrification rate. The inorganic N in the tree and shrub soils were lower in fall and summer, respectively, which was dependent on the seasonal variations in plant N uptake, soil N transformation, and N leaching. Thus, our results suggest that tree plantations could decrease soil inorganic N concentration and N leaching by altering both the quantity and quality of SOC and thereby potentially improve water quality in the riparian zone. PMID:25723959

Ye, Chen; Cheng, Xiaoli; Liu, Wenzhi; Zhang, Quanfa

2015-06-01

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Environmental assessment for the natural fluctuation of water level in Par Pond and reduced water flow in Steel Creek below L-Lake at the Savannah River Site  

International Nuclear Information System (INIS)

The Savannah River Operations Office Strategic Plan directs Savannah River Site (SRS) to find ways to reduce operating costs, and to determine what site infrastructure must be maintained and what infrastructure is surplus. Because of the mission change, L-Lake, Par Pond, and the river water system are no longer needed to support current missions and therefore provide an opportunity for operating cost reduction. If SRS determines that L-Lake, Par Pond, and the river water system are no longer needed to support future missions and are considered surplus, appropriate NEPA documentation will be prepared. The purpose of the proposed action in this Environmental Assessment is to begin an examination of the need for the Site's river water system by (1) developing data needed to evaluate the potential environmental impacts of further reducing or eliminating the flow demands from the Site's river water system and; (2) evaluating the potential of reducing operating costs by allowing the water level in Par Pond to fluctuate naturally through reduced pumping. This action also includes reducing the current flow rates from L-Lake to Steel Creek to natural stream flows while maintaining full pool. The recently approved Par Pond CERCLA Interim Action Proposed Plan (IAPP) committed to evaluate in a NEPA document the environmental consequences of this proposed action. This document evaluated the remediation of human health and ecological risks associated with the three year drawdown of Par Pond. Should any of the parameters sampled in the reservoir and streams (e.g., water quality, biota, etc.) exceed established threshold levels during the implementation of the proposed action, water would again be pumped into the reservoir to minimize any impacts by bringing the water level back to an appropriate level about 58.2 m (195 ft)

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Assessing soil heavy metal pollution in the water-level-fluctuation zone of the Three Gorges Reservoir, China.  

Science.gov (United States)

The water-level-fluctuation zone (WLFZ) between the elevations of 145-175 m in China's Three Gorges Reservoir has experienced a novel hydrological regime with half a year (May-September) exposed in summer and another half (October-April) submerged in winter. In September 2008 (before submergence) and June 2009 (after submergence), soil samples were collected in 12 sites in the WLFZ and heavy metals (Hg, As, Cr, Cd, Pb, Cu, Zn, Fe, and Mn) were determined. Enrichment factor (EF), factor analysis (FA), and factor analysis-multiple linear regression (FA-MLR) were employed for heavy metal pollution assessment, source identification, and source apportionment, respectively. Results demonstrate spatial variability in heavy metals before and after submergence and elements of As, Cd, Pb, Cu, and Zn are higher in the upper and low reaches. FA and FA-MLR reveal that As and Cd are the primary pollutants before submergence, and over 45% of As originates from domestic sewage and 59% of Cd from industrial wastes. After submergence, the major contaminants are Hg, Cd, and Pb, and traffic exhaust contributes approximately 81% to Hg and industrial effluent accounts about 36% and 73% for Cd and Pb, respectively. Our results suggest that increased shipping and industrial wastes have deposited large amounts of heavy metals which have been accumulated in the WLFZ during submergence period. PMID:21571427

Ye, Chen; Li, Siyue; Zhang, Yulong; Zhang, Quanfa

2011-07-15

27

Comparison between Neural Networks and Adaptive Neuro-fuzzy Inference System in Modeling Lake Kerkini Water Level Fluctuation Lake Management using Artificial Intelligence  

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Full Text Available This study presents lake Kerkini water level simulation. Water level depends on a large number of parameters and procedures which are usually complex or non-linear. Water level was calculated, by using a model based on visual basic language. The model took account of all parameters that contribute to water level. Simulation was achieved when the model output approximated the available measured values. Afterwards, the same project was implemented by using artificial intelligence methods. These are, artificial neural networks and adaptive neuro fuzzy inference system. The basic advantage of this implementation is the fact that the output is obtained without having to use all the parameters that contribute to the final result. This means that they can be implemented for modeling systems where the procedures are not fully known or when there is a large parameter number affecting the result. Both models showed a great performance in simulating water level fluctuation and they are also suggested for prediction.

Christos Evangelides

2011-01-01

28

Pattern and Biodiversity of Plant Community in Water-Level-Fluctuation Zone of Pengxi River After 156 m Impoundment of Three Gorges Reservoir  

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Full Text Available After impounding to altitude of 156 m, species, spatial pattern and biodiversity of plant community in water-level-fluctuation zone of Three Gorges Reservoir had significant changes. The plant community under altitude of 175 m beside Pengxi River and its tributary Baijia Stream in Kaixian County was studied from July to September, 2008. 108 herb sampling quadrates along five sampling transects, three beside Pengxi River and two beside Baijia Stream, were conducted. The results showed that there are 98 species of vascular plant belong to 38 families, 29 generas. 52 species of wetland plant were investigated. Therophytes(52.0% and cryptophyte (31.6% were the dominant compositions of Raunkiaer’s life. The plant community of study area belonged to 11 associations. Floodplain annual herb zone, Xanthium sibiricum zone, Paspalum paspaloides zone and Imperata cylindrica zone dispersed at the lateral side of Pengxi River and Baijia stream from riparian to altitude of 175 m. The variation and pattern of soil water content significantly influenced the distribution of plant community in water-level-fluctuation zone. There were a low herb biodiversity in water-lever fluctuation zone.

WANG Jian-xiu

2009-10-01

29

Influence of water level fluctuation on the mortality and aboveground biomass of the aquatic macrophyte Eleocharis interstincta (VAHL roemer et schults  

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Full Text Available The goal of this study was to study the biometric alterations of Eleocharis interstincta in response to water level fluctuations in Cabiúnas Lagoon, located on the northern coast of the state of Rio de Janeiro, in the municipality of Macaé. Three quadrats of 0.0625 m² were harvested every two weeks from June/1997 to June/1998; samples were separated into stems, dead stems (detritus and rhizome; lenghted, dried and weighted. The water level fluctuated seasonally in the macrophyte stand with two periods of drawdown. The first period occurred naturally at the end of winter and beginning of spring, when rainfall in the area was normally lowest. The second period of drawdown was the result of an artificial breaching of the sandbar that isolate the lagoon from the sea. The breach was made in the summer, at the time of highest rainfall, when the water level in the lagoon reached the maximum value recorded during the study (1.35 m. There was a strongly positive correlation of the water level with stems mean height and aboveground biomass, indicating that water level played an important role in the determination of these parameters. There was a significant difference between stem height (ANOVA; p < 0.001 and biomass (ANOVA; p < 0.001 in each sampling period, ranging from 143.9 cm and 338.8 g dry wt.m-2, before the sandbar opening, to 16.3 cm and 20.2 g dry wt.m-2 respectively after the sandbar breaching. The drastic variation of the water level, leading mass mortality of the stems, together with the lowest mean biomass/stem (0.057 g dry wt.individual-1, recorded after the sandbar breaching, did not represent a strong disturbance for E. interstincta, since the resilience time estimated for this population was about 30 days.

Santos Anderson Medeiros dos

2004-01-01

30

Lake Level Fluctuations Boost Toxic Cyanobacterial “Oligotrophic Blooms”  

Science.gov (United States)

Global warming has been shown to strongly influence inland water systems, producing noticeable increases in water temperatures. Rising temperatures, especially when combined with widespread nutrient pollution, directly favour the growth of toxic cyanobacteria. Climate changes have also altered natural water level fluctuations increasing the probability of extreme events as dry periods followed by heavy rains. The massive appearance of Dolichospermum lemmermannii (?=?planktonic Anabaena), a toxic species absent from the pelagic zone of the subalpine oligotrophic Lake Maggiore before 2005, could be a consequence of the unusual fluctuations of lake level in recent years. We hypothesized that these fluctuations may favour the cyanobacterium as result of nutrient pulses from the biofilms formed in the littoral zone when the lake level is high. To help verify this, we exposed artificial substrates in the lake, and evaluated their nutrient enrichment and release after desiccation, together with measurements of fluctuations in lake level, precipitation and D.lemmermannii population. The highest percentage of P release and the lowest C?P molar ratio of released nutrients coincided with the summer appearance of the D.lemmermannii bloom. The P pulse indicates that fluctuations in level counteract nutrient limitation in this lake and it is suggested that this may apply more widely to other oligotrophic lakes. In view of the predicted increase in water level fluctuations due to climate change, it is important to try to minimize such fluctuations in order to mitigate the occurrence of cyanobacterial blooms. PMID:25295866

Callieri, Cristiana; Bertoni, Roberto; Contesini, Mario; Bertoni, Filippo

2014-01-01

31

Lake level fluctuations boost toxic cyanobacterial "oligotrophic blooms".  

Science.gov (United States)

Global warming has been shown to strongly influence inland water systems, producing noticeable increases in water temperatures. Rising temperatures, especially when combined with widespread nutrient pollution, directly favour the growth of toxic cyanobacteria. Climate changes have also altered natural water level fluctuations increasing the probability of extreme events as dry periods followed by heavy rains. The massive appearance of Dolichospermum lemmermannii (?=?planktonic Anabaena), a toxic species absent from the pelagic zone of the subalpine oligotrophic Lake Maggiore before 2005, could be a consequence of the unusual fluctuations of lake level in recent years. We hypothesized that these fluctuations may favour the cyanobacterium as result of nutrient pulses from the biofilms formed in the littoral zone when the lake level is high. To help verify this, we exposed artificial substrates in the lake, and evaluated their nutrient enrichment and release after desiccation, together with measurements of fluctuations in lake level, precipitation and D. lemmermannii population. The highest percentage of P release and the lowest C:P molar ratio of released nutrients coincided with the summer appearance of the D. lemmermannii bloom. The P pulse indicates that fluctuations in level counteract nutrient limitation in this lake and it is suggested that this may apply more widely to other oligotrophic lakes. In view of the predicted increase in water level fluctuations due to climate change, it is important to try to minimize such fluctuations in order to mitigate the occurrence of cyanobacterial blooms. PMID:25295866

Callieri, Cristiana; Bertoni, Roberto; Contesini, Mario; Bertoni, Filippo

2014-01-01

32

Habitat Selection by African Buffalo (Syncerus caffer) in Response to Landscape-Level Fluctuations in Water Availability on Two Temporal Scales  

OpenAIRE

Seasonal fluctuations in water availability cause predictable changes in the profitability of habitats in tropical ecosystems, and animals evolve adaptive behavioural and spatial responses to these fluctuations. However, stochastic changes in the distribution and abundance of surface water between years can alter resource availability at a landscape scale, causing shifts in animal behaviour. In the Okavango Delta, Botswana, a flood-pulsed ecosystem, the volume of water entering the system dou...

Bennitt, Emily; Bonyongo, Mpaphi Casper; Harris, Stephen

2014-01-01

33

[Sediment risk assessment and heavy metal source analysis in typical country water level fluctuated zone (WLFZ) of the Three Gorges].  

Science.gov (United States)

Typical country WLFZ in Zhongxian located in the core region of the Three Gorges Reservoir was chosen as research subject in this study. In July 2012, sediment samples of WLFZ were collected after dam water level dropped. Heavy metals were analyzed for sediment potential risk assessment and then applied for sources analysis in this area, which supplied basic data for non-point pollutants control. The results showed that As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn ranged in 155-160 m:5.17-14.81, 0.06-0.57, 8.55-20.56, 62.79-93.04, 15.38-60.97, 425.72-782.32, 21.34-48.5, 23.03-43.39 and 57.78-130.10 mg x kg(-1), and 170-175 m: 7.05-12.57, 0.17-0.33, 10.71-18.89, 65.22-92.89, 18.89-42.91, 74.06-774.41, 22.47-42.49, 24.17-29.23, 55.67-103.18 mg x kg(-1), respectively. Index of geo-accumulation (Igeo) suggested the accumulation orders were Cd > Co > Mn > As > Cu > Pb > Zn in 155-160m WLFZ and Co > Mn > Cd > As in 170-175 m WLFZ. Sediment pollution index (SPI) showed that sediments in 155-160 m WLFZ had higher potential risk than that of 170-175 m with the highest risk appeared in 155-166 m WLFZ site located downstream of Zhongxian. In 155-160 m WLFZ, Cr, Cu, Pb and Zn were mainly originated from natural resources, while As, Ni, Cd, Co and Mn were possibly sourced from upland water. In contrast, in 170-175 m WLFZ, Cr, Ni, Pb and Zn in the sediment came from natural resources, while Cd, As, Co, Mn and Cu were probably rooted from both agricultural non-point source and upland water. PMID:24720202

Ao, Liang; Lei, Bo; Wang, Ye-Chun; Zhou, Xie; Zhang, Sheng

2014-01-01

34

Level Dynamics and Universality of Spectral Fluctuations  

OpenAIRE

The spectral fluctuations of quantum (or wave) systems with a chaotic classical (or ray) limit are mostly universal and faithful to random-matrix theory. Taking up ideas of Pechukas and Yukawa we show that equilibrium statistical mechanics for the fictitious gas of particles associated with the parametric motion of levels yields spectral fluctuations of the random-matrix type. Previously known clues to that goal are an appropriate equilibrium ensemble and a certain ergodicit...

Braun, Peter; Gnutzmann, Sven; Haake, Fritz; Kus, Marek; Zyczkowski, Karol

2000-01-01

35

Assessing heavy metal pollution in the water level fluctuation zone of China's Three Gorges Reservoir using geochemical and soil microbial approaches.  

Science.gov (United States)

The water level fluctuation zone (WLFZ) in the Three Gorges Reservoir is located in the intersection of terrestrial and aquatic ecosystems, and assessing heavy metal pollution in the drown zone is critical for ecological remediation and water conservation. In this study, soils were collected in June and September 2009 in natural recovery area and revegetation area of the WLFZ, and geochemical approaches including geoaccumulation index (I (geo)) and factor analysis and soil microbial community structure were applied to assess the spatial variability and evaluate the influence of revegetation on metals in the WLFZ. Geochemical approaches demonstrated the moderate pollutant of Cd, the slight pollutant of Hg, and four types of pollutant sources including industrial and domestic wastewater, natural rock weathering, traffic exhaust, and crustal materials in the WLFZ. Our results also demonstrated significantly lower concentrations for elements of As, Cd, Pb, Zn, and Mn in the revegetation area. Moreover, soil microbial community structure failed to monitor the heavy metal pollution in such a relatively clean area. Our results suggest that revegetation plays an important role in controlling heavy metal pollution in the WLFZ of the Three Gorges Reservoir, China. PMID:22311560

Ye, Chen; Li, Siyue; Zhang, Yulong; Tong, Xunzhang; Zhang, Quanfa

2013-01-01

36

Coastal eolian landforms and sea level fluctuations  

Science.gov (United States)

This paper is dedicated to correlation of the formation of coastal marine landforms with sea level fluctuations and climate changes in the last millennium using the southeastern Baltic region as an example. The morphological analysis of spits and historical evidence reveal three sea level oscillations in its evolution. It is shown that the sea level rise against the background of the sandy material excess in the coastal zone and optimum angle of the prevailing land-directed wind are the main factors responsible for accumulation of the thickest sandy formations. The recent climate warming and related sea level rise provoke global destabilization of coastal dune massifs.

Badyukova, E. N.; Solovieva, G. D.

2015-02-01

37

Advancing Analysis of Spatio-Temporal Variations of Soil Nutrients in the Water Level Fluctuation Zone of China’s Three Gorges Reservoir Using Self-Organizing Map  

Science.gov (United States)

The ~350 km2 water level fluctuation zone (WLFZ) in the Three Gorges Reservoir (TGR) of China, situated at the intersection of terrestrial and aquatic ecosystems, experiences a great hydrological change with prolonged winter inundation. Soil samples were collected in 12 sites pre- (September 2008) and post submergence (June 2009) in the WLFZ and analyzed for soil nutrients. Self-organizing map (SOM) and statistical analysis including multi-way ANOVA, paired-T test, and stepwise least squares multiple regression were employed to determine the spatio-temporal variations of soil nutrients in relation to submergence, and their correlations with soil physical characteristics. Results showed significant spatial variability in nutrients along ~600 km long shoreline of the TGR before and after submergence. There were higher contents of organic matter, total nitrogen (TN), and nitrate (NO3-) in the lower reach and total phosphorus (TP) in the upper reach that were primarily due to the spatial variations in soil particle size composition and anthropogenic activities. Submergence enhanced soil available potassium (K), while significantly decreased soil N, possibly due to the alterations of soil particle size composition and increase in soil pH. In addition, SOM analysis determined important roles of soil pH value, bulk density, soil particle size (i.e., silt and sand) and nutrients (TP, TK, and AK) on the spatial and temporal variations in soil quality. Our results suggest that urban sewage and agricultural runoffs are primary pollutants that affect soil nutrients in the WLFZ of TGR. PMID:25789612

Ye, Chen; Li, Siyue; Yang, Yuyi; Shu, Xiao; Zhang, Jiaquan; Zhang, Quanfa

2015-01-01

38

Fluctuation of Groundwater Levels and Recharge Patterns in Northern Ghana  

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Full Text Available Evaluating groundwater levels and recharge patterns is part of sustainably managing the water supply and predicting the possibility of water shortages, especially in light of climate change, extreme events (floods/droughts, increasing population and development. In the northern region of Ghana, groundwater is increasingly relied upon as a source of potable water for rural populations, but seasonal and inter-annual fluctuations of groundwater levels and recharge patterns are not always known. The fluctuation of groundwater levels on a seasonal basis shows that groundwater levels at all sites increase in response to seasonal precipitation. On an annual basis, all sites show an overall net decline of groundwater levels over the study period, which may be associated with below-average departures of precipitation during five of the seven study years. The variability of recharge patterns among five sites is attributed to the spatio-temporal variability of precipitation and hydrogeologic site uniqueness. The overarching potential benefit of this study is to facilitate closing knowledge gaps and contribute to a foundation for a more robust evaluation of groundwater resources in the area, especially as more data become available.

Alexandra Lutz

2014-12-01

39

Hydrological processes and water resources management in a dryland environment IV: Long-term groundwater level fluctuations due to variation in rainfall  

Directory of Open Access Journals (Sweden)

Full Text Available To evaluate the effects of variations in rainfall on groundwater, long-term rainfall records were used to simulate groundwater levels over the period 1953-96 at an experimental catchment in south-east Zimbabwe. Two different modelling methods were adopted. Firstly, a soil water balance model (ACRU simulated drainage from daily rainfall and evaporative demand; groundwater levels were predicted as a function of drainage, specific yield and water table height. Secondly, the cumulative rainfall departure method was used to model groundwater levels from monthly rainfall. Both methods simulated observed groundwater levels over the period 1992-96 successfully, and long-term simulated trends in historical levels were comparable. Results suggest that large perturbations in groundwater levels area a normal feature of the response of a shallow aquifer to variations in rainfall. Long-term trends in groundwater levels are apparent and reflect the effect of cycles in rainfall. Average end of dry season water levels were simulated to be almost 3 m higher in the late 1970s compared to those of the early 1990s. The simulated effect of prolonged low rainfall on groundwater levels was particularly severe during the period 1981-92 with a series of low recharge years unprecedented in the earlier record. More recently, above average rainfall has resulted in generally higher groundwater levels. The modelling methods described may be applied in the development of guidelines for groundwater schemes to help ensure safe long-term yields and to predict future stress on groundwater resources in low rainfall periods; they are being developed to evaluate the effects of land use and management change on groundwater resources.

J. A. Butterworth

1999-01-01

40

Charge Fluctuations on Membrane Surfaces in Water  

CERN Document Server

We generalize the predictions for attractions between over-all neutral surfaces induced by charge fluctuations/correlations to non-uniform systems that include dielectric discontinuities, as is the case for mixed charged lipid membranes in an aqueous solution. We show that the induced interactions depend in a non-trivial way on the dielectric constants of membrane and water and show different scaling with distance depending on these properties. The generality of the calculations also allows us to predict under which dielectric conditions the interaction will change sign and become repulsive.

Menes, R; Stein, B; Menes, Rebecca; Pincus, Philip; Stein, Bean

2000-01-01

41

Glacier fluctuations, global temperature and sea-level change  

OpenAIRE

The current world-wide glacier retreat is a clear sign of global warming. In addition, glaciers contribute to sea-level rise as a consequence of the current retreat. In this thesis we use records of past glacier fluctuations to reconstruct past climate variations and the glacier contribution to sea-level change. Firstly, a coherent data set of world-wide glacier fluctuations over the past centuries is compiled. Most available information of glacier fluctuations concerns glacier length flu...

Leclercq, P. W.

2012-01-01

42

Level density fluctuations of interacting bosons  

International Nuclear Information System (INIS)

By the use of DELTA3 and sigma2(k) statistics a comparison is made between the fluctuation properties of a two-body boson ensemble and the Gaussian orthogonal ensemble (GOE). With the two statistics no significant differences between the two ensembles have been found

43

Spatial-temporal Dynamics of Vegetation in the Newly Created Water-level-fluctuation Zone of Three Gorges Reservoir:a Case Study in Baijia Stream, Kaixian County, China  

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Full Text Available "After impoundent of the Three Gorges Reservoir, a large permanent sample plot was placed in its water-level-fluctuation zone beside Baijia Stream, Kaixian County, China. Vegetation in the plot was investigated in the summer of 2008,2009 and 2010. The result indicated that community' s component, biodiversity and aboveground biomass showed obvious spatial-temporal dynamics. Total spiecies number of vascular flora inside decreased yearly, from 52 species in 2008 to 41 species in 2009 and to 35 species in 2010. The area below 156 m in elevation was dominated by Paspalum paspaloides andXanthium sibiricum in 2008. However, Paspalum paspaloides was rapid replaced by Cynodon dactylo in 2009 and X. sibiricum expanded its distribution in upper area of the plot. In 2010, X. sibiricum depressed its population in lower areas of the plot as the Three Gorges Reservoir started to impound half month earlier in the winter of 2009 and decreased seed bank for its germination. Shannon-Wiener Index increased as elevation according to the data of 2009 and 2010, which reflected the influ-ence of submerged gradient. Aboveground biomass of vegetation in each elevation zone of the plot indicated great variation.Key words: Three Gorges Reservoir; water-level-fluctuation zone; vegetation; spatial-temporal dynamics; biodiversity"

YUAN Xing-zhong

2012-05-01

44

Spatial and temporal fluctuations in water levels of tundra ponds: baseline studies associated with a large-scale flooding and draining experiment in northern Alaska  

Science.gov (United States)

To better understand how soil moisture affects carbon balance and other biophysical processes in tundra ecosystems, a large-scale (ca. 60ha) flooding and draining experiment was initiated in Spring 2005 on the Barrow Environmental Observatory in northern Alaska. During 2005 the experimental area was studied in an un-manipulated state. In Spring 2006, the study area will be divided into three soil moisture conditions: a drained area (-10cm) at the north end (ca. 20ha), a central un-manipulated control area (ca. 20ha), and a flooded area (+10cm) at the south end of the basin (ca. 20ha). In preparation for initiating the manipulation planned for 2006, the water level of various tundra ponds, both within and outside of the experimental area, was measured every few days throughout the summer of 2005 using a Differential Global Positioning System (DGPS). This study will report an initial analysis of these data, which will be used to engineer, monitor and regulate water levels within the experimental manipulation.

Jaurrieta, E.; Laija, E.; Tweedie, C. E.

2005-12-01

45

Hydrophobic nanoconfinement suppresses fluctuations in supercooled water.  

Science.gov (United States)

We perform very efficient Monte Carlo simulations to study the phase diagram of a water monolayer confined in a fixed disordered matrix of hydrophobic nanoparticles between two hydrophobic plates. We consider different hydrophobic nanoparticle concentrations c. We adopt a coarse-grained model of water that, for c = 0, displays a first-order liquid-liquid phase transition (LLPT) line with negative slope in the pressure-temperature (P-T) plane, ending in a liquid-liquid critical point at about 174 K and 0.13 GPa. We show that upon increase of c the liquid-gas spinodal and the temperature of the maximum density line are shifted with respect to the c = 0 case. We also find dramatic changes in the region around the LLPT. In particular, we observe a substantial (more than 90%) decrease of isothermal compressibility, thermal expansion coefficient and constant-pressure specific heat upon increasing c, consistent with recent experiments. Moreover, we find that a hydrophobic nanoparticle concentration as small as c = 2.4% is enough to destroy the LLPT for P ? 0.16 GPa. The fluctuations of volume apparently diverge at P ? 0.16 GPa, suggesting that the LLPT line ends in an LL critical point at 0.16 GPa. Therefore, nanoconfinement reduces the range of P-T where the LLPT is observable. By increasing the hydrophobic nanoparticle concentration c, the LLPT becomes weaker and its P-T range smaller. The model allows us to explain these phenomena in terms of a proliferation of interfaces among domains with different local order, promoted by the hydrophobic effect of the water-hydrophobic-nanoparticle interfaces. PMID:22277682

Strekalova, E G; Mazza, M G; Stanley, H E; Franzese, G

2012-02-15

46

Impacts of Water Level Fluctuations on Kokanee Reproduction in Flathead Lake; Effects of Operation of Kerr and Hungry Horse Dam on Reproductive Success, 1983 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

Koktneesalmon (Oncorhvnchusnerka), the land-locked form of sockeye salmon, were originally introduced to Flathead Lake in 1916. My 1933, kokanee had become established in the lake and provided a popular summer trolling fishery as well as a fall snagging fishery in shoreline areas. Presently, Flathead Lake supports the second highest fishing pressure of any lake or reservoir in Montana (Montana Department of Fish and Game 1976). During 1981-82, the lake provided 168,792 man-days of fishing pressure. Ninety-two percent of the estimated 536,870 fish caught in Flathead Lake in 1981-82 were kokanee salmon. Kokanee also provided forage for bull trout seasonally and year round for lake trout. Kokanee rear to maturity in Flathead Lake, then return to various total grounds to spawn. Spawning occurred in lake outlet streams, springs, larger rivers and lake shoreline areas in suitable but often limited habitat. Shoreline spawning in Flathead Lake was first documented in the mid-1930's. Spawning kokanee were seized from shoreline areas in 1933 and 21,000 cans were processed and packed for distribution to the needy. Stefanich (1953 and 1954) later documented extensive but an unquantified amount of spawning along the shoreline as well as runs in Whitefish River and McDonald Creek in the 1950's. A creel census conducted in 1962-63 determined 11 to 13 percent of the kokanee caught annually were taken during the spawning period (Robbins 1966). During a 1981-82 creel census, less than one percent of the fishermen on Flathead Lake were snagging kokanee (Graham and Fredenberg 1982). The operation of Kerr Dam, located below Flathead Lake on the Flathead River, has altered seasonal fluctuations of Flathead Lake. Lake levels presently remain high during kokanee spawning in November and decline during the incubation and emergence periods. Groundwater plays an important role in embryo and fry survival in redds of shoreline areas exposed by lake drawdown. Stefanich (1954) and Domrose (1968) found live eggs and fry only in shoreline spawning areas wetted by groundwater seeps. Impacts of the operation of Kerr Dam on lakeshore spawning have not been quantified. Recent studies have revealed that operation of Hungry Horse Dam severely impacted successful kokanee spawning and incubation in the Flathead River above Flathead Lake (Graham et al. 1980, McMullin and Graham 1981, Fraley and Graham 1982 and Fraley and McMullin 1983). Flows from Hungry Horse Dam to enhance kokanee reproduction in the river system have been voluntarily met by the Bureau of Reclamation since 1981. In lakeshore spawning areas in other Pacific Northwest systems, spawning habitat for kokanee and sockeye salmon was characterized by seepage or groundwater flow where suitable substrate composition existed (Foerster 1968). Spawning primarily occurred in shallower depths (<6 m) where gravels were cleaned by wave action (Hassemer and Rieman 1979 and 1980, Stober et al. 1979a). Seasonal drawdown of reservoirs can adversely affect survival of incubating kokanee eggs and fry spawned in shallow shoreline areas. Jeppon (1955 and 1960) and Whitt (1957) estimated 10-75 percent kokanee egg loss in shoreline areas of Pend Oreille Lake, Idaho after regulation of the upper three meters occurred in 1952. After 20 years of operation, Bowler (1979) found Pend Oreille shoreline spawning to occur in fewer areas with generally lower numbers of adults. In studies on Priest Lake, Idaho, Bjornn (1957) attributed frozen eggs and stranded fry to winter fluctuations of the upper three meters of the lake. Eggs and fry frozen during winter drawdown accounted for a 90 percent loss to shoreline spawning kokanee in Donner Lake, California (Kimsey 1951). Stober et al. (1979a) determined irrigation drawdown of Banks Lake, Washington reduced shoreline survival during five of the seven years the system was studied. The goal of this phase of the study was to evaluate and document effects of the operation of Kerr Dam on kokanee shoreline reproduction in Flathead Lake. Specific objectives to meet this goal ar

Decker-Hess, Janet; McMullin, Steve L.

1983-11-01

47

Air encapsulation. II. Profile water storage and shallow water table fluctuations  

International Nuclear Information System (INIS)

In a wet soil, volumetric encapsulated air contents can easily approach 0.06 m3 m-3. The objective of this study was to determine, through simulation, the effect of air encapsulation on profile water storage and shallow water table fluctuations and whether air encapsulation should be considered in modeling field events. Using a two-dimensional soil moisture code that included a routine designed to model air encapsulation, the authors simulated profile water storage changes during hypothetical rainfall events and water table responses during actual rainfall events. The simulation results indicated that, following the infiltration of 10 mm of water, profile moisture content differences with and without air encapsulation would be 3 m-3 and thus may not be measurable in the field with a neutron probe. Water table levels, however, rose significantly higher in the profile when air was encapsulated. Depending on the initial depth of the water table and the moisture characteristic, the water table rises were two to five times those when air was not encapsulated. For water tables located within 1.3 m of the surface, application of the model to actual rainfall events improved the fit to the measured water table data. In those situations where water table level predictions are important (e.g., wetlands, stream banks), researchers should consider air encapsulation in their analysis of water table fluctuations

48

Water level instrumentation simulation  

International Nuclear Information System (INIS)

Through simulation, evaluations of system performance can be made to increase efficiency, reduce costs, enhance safety and provide effective training. A full function simulation for evaluating water level measurement requires modeling the physical process, the process instrumentation response and where appropriate, the human input/response. This paper examines a full function application simulating the primary system water level in a Boiling Water Reactor (BWR). The physical processes associated with BWR vessel level response are modeled with the Modular Accident Analysis Program (MAAP). The MAAP code is used as the basis for providing primary system and containment thermal-hydraulic response to a compendium of expected plant transients. The BWR vessel level instruments is modeled with the FAI developed Instrumentation PACkage (IPAC). With the thermal-hydraulic input from MAAP, the IPAC software models the various phenomena associated with water level measurements including the effects due to: (1) instrument channel calibration, (2) instrument drift and (3) containment (drywell) environmental effects. This paper discusses the IPAC models (instrumentation components) along with the factors which influence the mass balance of water in the downcomer region. A comparison of the BWR vessel water level complete simulation package to data from a simulated BWR plant transient culminates the discussion of this paper. The full function simulation package presented in this papersimulation package presented in this paper, enables a software-based representation of the BWR vessel level to be evaluated under various hypothetical plant conditions including normal, accident, and severe accident events. (author)

49

Groundwater Level Fluctuation Forecasting in Birjand Aquifer Using Artificial Neural Network  

Science.gov (United States)

Artificial Neural Networks (ANNs) are being used increasingly to predict and forecast water resources variables such as groundwater levels. In this paper using artificial neural network three objective including determination of the influential parameters which impact fluctuation of groundwater level in birjand aquifer, investigation of the effect of temporal and spatial information by considering time series (9 years) and simulation of the fluctuation groundwater level in three selected piezometers are recognized. The reasonably good prediction of piezometric level simulated based on ANN using FNN_LM by selection of effective parameters and optimal time lag

Mirarabi, A.; Nakhaei, M.

2009-04-01

50

Fluctuations of water near extended hydrophobic and hydrophilic surfaces  

OpenAIRE

We use molecular dynamics simulations of the SPC-E model of liquid water to derive probability distributions for water density fluctuations in probe volumes of different shapes and sizes, both in the bulk as well as near hydrophobic and hydrophilic surfaces. Our results are obtained with a biased sampling of coarse-grained densities that is easily combined with molecular dynamics integration algorithms. Our principal result is that the probability for density fluctuations of water near a hydr...

Patel, Amish J.; Varilly, Patrick; Chandler, David

2009-01-01

51

Artificial neural network modeling of water table depth fluctuations  

Science.gov (United States)

Three types of functionally different artificial neural network (ANN) models are calibrated using a relatively short length of groundwater level records and related hydrometeorological data to simulate water table fluctuations in the Gondo aquifer, Burkina Faso. Input delay neural network (IDNN) with static memory structure and globally recurrent neural network (RNN) with inherent dynamical memory are proposed for monthly water table fluctuations modeling. The simulation performance of the IDNN and the RNN models is compared with results obtained from two variants of radial basis function (RBF) networks, namely, a generalized RBF model (GRBF) and a probabilistic neural network (PNN). Overall, simulation results suggest that the RNN is the most efficient of the ANN models tested for a calibration period as short as 7 years. The results of the IDNN and the PNN are almost equivalent despite their basically different learning procedures. The GRBF performs very poorly as compared to the other models. Furthermore, the study shows that RNN may offer a robust framework for improving water supply planning in semiarid areas where aquifer information is not available. This study has significant implications for groundwater management in areas with inadequate groundwater monitoring network.

Coulibaly, Paulin; Anctil, FrançOis; Aravena, Ramon; BobéE, Bernard

2001-04-01

52

Ground water head fluctuations in coastal aquifers. Sensitivity analysis and hydromechanical effects.  

Science.gov (United States)

Fluctuations of ground water head in response to sea level fluctuations have long been considered very informative of aquifer diffusivity and connectivity to the sea, which is critical for coastal aquifers management. We present a sensitivity analysis of the inland dampening of the fluctuations amplitude and of their time shift to show that their interpretation is quite robust. That is, fluctuations are not overly sensitive to heterogeneity or to density variations in the case of unconfined aquifers. However, fluctuations are observed in confined aquifers that are hydraulically connected to the sea far off shore. Such response is hydro-mechanically driven by the fluctuations in mechanical load over the sea floor caused by sea level fluctuations. We present the analytical solution to this problem that generalizes existing solutions. The solution contains a hydraulic and a mechanical response terms. The former would inform about the off-shore distance to the sea-aquifer connection, but is dampened in most practical situations, when the mechanical effect becomes significant. In fact, the amplitude of tide-induced head fluctuations at the shore for such cases is approximately one half of the tidal fluctuation. Therefore, large fluctuations cannot be associated to good sea-aquifer hydraulic connection. Fortunately, the amplitude and phase shift are easy to simulate and quite sensitive to aquifer diffusivity and aquitard sorptivity. Therefore, they can be reliably used for large scale model calibration, provided that a good conceptual model and other model parameters are available.

Carrera Ramirez, J.; Guarracino, L.; Slooten, L. J.; Vazquez-Sune, E.

2012-12-01

53

Capillary effect on water table fluctuations in unconfined aquifers  

Science.gov (United States)

Parlange and Brutsaert (1987) derived a modified Boussinesq equation to account for the capillary effect on water table dynamics in unconfined aquifers. Barry et al. (1996) solved this equation subject to a periodic boundary condition. Their solution shows significant influence of capillarity on water table fluctuations, which evolve to finite-amplitude standing waves at the high frequency limit. Here we propose a new governing equation for the water table, which considers both horizontal and vertical flows in an unsaturated zone of finite thickness. An approximate analytical solution for periodic water table fluctuations based on the new equation was derived. In agreement with previous results, the analytical solution shows that the unsaturated zone's storage capacity permits water table fluctuations to propagate more readily than predicted by the Boussinesq equation. Furthermore, the new solution reveals a capping effect of the unsaturated zone on both the amplitude and phase of the water table fluctuations as well as the water table overheight. Due to the finite thickness of the unsaturated zone, the capillary effect on water table fluctuations is modified mainly with reduced amplitude damping and phase shift.

Kong, Jun; Shen, Cheng-Ji; Xin, Pei; Song, Zhiyao; Li, Ling; Barry, D. A.; Jeng, D.-S.; Stagnitti, F.; Lockington, D. A.; Parlange, J.-Y.

2013-05-01

54

Tides and Water Levels  

Science.gov (United States)

This site serves as a gateway to three sections devoted to learning about tides and water levels: an online tutorial, an list of links to tidal resources, and formal lesson plans. The tutorial is an overview of the complex systems that govern the movement of tides and water levels. It is content rich, is presented in easy-to-understand language, and includes many illustrative and interactive graphics to visually enhance the text. The links direct users to specific tidal and current data offered within the National Ocean Service and National Oceanic and Atmospheric Administration's family of products. Lesson plans integrate information presented in the tutorial with online data. These lesson plans have been developed for students in grades 9-12 and focus on the forces that cause and effect tides, analysis of the variations in tidal patterns and what conditions may cause them, and the effect of lunar cycles on living organisms.

55

Diurnal Water Table Fluctuations: An Underutilized Indicator of Ground-water Consumption by Plants  

Science.gov (United States)

Hydrographs from shallow wells in areas with phreatophytes frequently display a distinctive pattern of diurnal fluctuations. Although first linked to variations in plant water use early in the last century, these diurnal fluctuations have received relatively little attention in the ecohydrology literature. In particular, little attention has been given to exploiting the information embedded in the water-level data to improve understanding of plant water use. Results from two field sites in western Kansas will be presented to demonstrate the insights that can be gleaned from these fluctuations. At one site the vegetation is representative of the native riparian-zone assemblage found over much of the Great Plains (major phreatophyte is the cottonwood [ Populus spp.]), whereas at the other site the vegetation is dominated by invasive species (salt cedar [ Tamarix spp.] and Russian olive [ Elaeagnus angustifoli]). Both sites have a network of shallow wells and neutron probe access tubes for monitoring water-table position and moisture content, respectively. The onset and termination of ground-water use by plants during the growing season is readily identifiable at both sites. Data from the first site show that the maximum depth from which phreatophytes can draw water depends on the previous hydrologic conditions experienced at the site, and not the physiological limits of the plant. Phreatophyte control actions (mulch cutting and chemical treatment) have recently been applied in a sequential fashion to a portion of the second site. The initial impact of those actions on ground-water consumption was not as large as expected, suggesting that forbs and grasses, which were not significantly impacted by these actions, also use substantial amounts of ground water. The magnitude of the diurnal fluctuations ranges appreciably between the sites, and even between wells at the same site. A portion of this difference can be attributed to variations in plant water uptake across a site. Often, however, a more important factor is variation in the specific yield of the sediments in the vicinity of the water table. Thus, the hydrogeology of the shallow subsurface cannot be ignored in interpretations of the fluctuations.

Bauer, J. P.; Shea, J.; Keller, J.; Butler, J. J.; Kluitenberg, G.; Whittemore, D. O.

2005-12-01

56

Water level control device in nuclear reactor  

International Nuclear Information System (INIS)

Upon start-up and shutdown of a BWR type reactor, the reactor pressure often varies greatly, by which the water level in the reactor also varies greatly. In the conventional water level control method, althogh the change in the water level of the reactor is detected and calculated for the control, it can not sometime follow after the remarkable water level change due to the delay in the calculation. The present invention has been made taking notice of this. That is, an additon/subtraction calculator that conducts addition/subtraction by adding the output of a reactor pressure detector is additionally disposed to a conventional control system using a water level control device. Thus, the opening degree for the feedwater control valve or the discharge water control valve is directly changed depending on the change of the pressure in the reactor. Since the output signal of the reactor water level controller is compensated previously by the signal for the fluctuation of the reactor pressure, rapid response of the water level control can be improved to minimize the water level change. (K.M.)

57

Water level detection pipeline  

International Nuclear Information System (INIS)

In the present invention, water levels of a feedwater heater and a drain tank in a nuclear power plant are detected at high accuracy. Detection pipeline headers connected to the upper and lower portions of a feedwater heater or a drain tank are connected with each other. The connection line is branched at appropriate two positions and an upper detection pipeline and a lower detection pipeline are connected thereto, and a gauge entrance valve is disposed to each of the detection pipelines. A diaphragm of a pressure difference generator is connected to a flange formed to the end portion. When detecting the change of water level in the feedwater heater or the drain tank as a change of pressure difference, gauge entrance valves on the exit side of the upper and lower detection pipelines are connected by a connection pipe. The gauge entrance valve is closed, a tube is connected to the lower detection pipe to inject water to the diaphragm of the pressure difference generator passing through the connection pipe thereby enabling to calibrate the pressure difference generator. The accuracy of the calibration of instruments is improved and workability thereof upon flange maintenance is also improved. (I.S.)

58

[Effects of turbulent fluctuation intensity on the growth of algae and water environment].  

Science.gov (United States)

Through a self-designed vertically oscillating grid experiment device, the experiment was carried out to research the effects of the turbulence fluctuation intensity on the growth of algae and water environment in the water with adequate nutrients by changing the vibration frequency under a certain light and temperature conditions. The results showed that: the turbulent fluctuation has significant effects on algae growing that weak turbulence fluctuation can promote the growth of algae and strong turbulence fluctuation will inhibit the growth of algae in the range of experimental level. With the increase of the turbulent fluctuation intensity, the peak of algal biomass gradually delayed. Changes of nitrogen and phosphorus in the experimental process have significant differences, when the vibration frequency was up to 2.0 Hz, the maximum reduction of TN and TP were 55.2% and 69.0% lower compared with 0.5 Hz, which was closely associated with the growth of algae. With the intensity of turbulent fluctuation increases, nitrogen-phosphorus ratio first increases and then decreases corresponding to the peak of the algal biomass. Turbulent fluctuation can promote the pH and, dissolved oxygen quickly adjusted to the level of algae growing required, and the most appropriate value remains unchanged. PMID:23914525

Lei, Yu; Long, Tian-yu; San, Lei; An, Qiang; Huang, Ning-qiu

2013-05-01

59

Experimental study of free level fluctuations in 1/4 scale reactor assembly model of PFBR  

International Nuclear Information System (INIS)

The construction pf Prototype Fast Breeder Reactor (PFBR), a 500 MWe liquid sodium cooled reactor has commenced at Kalpakkam in India. PFBR is a pool type reactor with two secondary loops. The primary sodium is contained within a 12.8 m diameter and 12.7 m high main vessel. The inner vessel separates the not and cold pools. The primary components like pumps, Control Plug, IHXs, DHXs, etc. are immersed in the reactor pool. Free level in the reactor pool is susceptible to fluctuations due to interaction of sodium stream from the core with the free surface and flow induced vortex shedding of the immersed structures like pump, IHX etc, in the hot pool. Due to free level fluctuations, the components immersed in sodium will alternately see hot sodium (at 820 k) and cooler argon cover gas) (at 670 K) at the sodium/argon interface. These temperature fluctuations can lead to thermal fatigue of the immersed components. Hence, it is required to assess the characteristics of free level fluctuations to understand their effect of the reactor components. In order to investigate various thermal hydraulic phenomena of PFBR, a large scale (1/4 scale) model of reactor primary circuit, which uses water as the working fluid, is constructed for experimental verification of thermal hydraulic behavior of the reactor. An experimental study was carried out in the above model to determine the magnitude and frequency of the free level fluctuations at different locations in the hot pool. The studferent locations in the hot pool. The study was conducted with Froude similitude. The free level fluctuations were measured using specially developed and calibrated conductivity probes. The experimental data were analyzed statistically. the model results were transposed to the reactor condition using appropriate similarity laws. It was observed that the free level fluctuations are not uniform in the hot pool and vary at different locations in the pool. The minimum peak-to-peak amplitude of fluctuations is about 38 mm at different locations if the pool. the minimum peak-to-peak amplitude of fluctuations is about 38 mm near the IHX and maximum is 82 mm in the vicinity of the control Plug for nominal operating conditions. The frequency of fluctuations was found to be less than 1.5 Hz. This paper brings out the details of the model, similarity criteria for the studies, instrumentation involved and the analysis of results obtained. (author)

60

The statistics of electric field fluctuations in liquid water  

OpenAIRE

Abstract Electric field fluctuations play a major role in dissociation reactions in liquid water and determine its vibrational spectroscopic response. Here, we study the statistics of electric fields in liquid water using molecular dynamics computer simulations with a particular focus on the strong but rare fields that drive dissociation. Our simulations indicate that the important contributions to the electric field acting on OH bonds stem from water molecules less than 7 ? away...

Reischl, Bernhard; Ko?finger, Ju?rgen; Dellago, Christoph

2009-01-01

61

Estimation of groundwater evaportranspiration using diurnal water table fluctuations in the Mu Us Desert, northern China  

Science.gov (United States)

Groundwater evapotranspiration (ETg) is a significant component of water balance analysis in desert areas. Estimation of ETg using diurnal water table fluctuations, i.e. the White method, is considered simple and straightforward, but it was seldom applied in desert areas. In this study, long-term and high-resolution groundwater level data were used to estimate ETg rate at two sites covered by typical desert plants Salix psammophila and Artemisia ordosica, respectively, in the Mu Us Desert in northern China. The specific yield (Sy) was derived from a drainage experiment in laboratory. The results showed that the water demand of S. psammophila could result in a weak but identifiable diurnal fluctuation of water table that was 2.35 m below the land surface, reasonable estimates of ETg could be derived from the White method, and the level of the ETg corresponded with the plant growth stages. However, the water table data from the area covered by A. ordosica did not show diurnal fluctuation during the growing season. The White method is good for the desert areas where groundwater use by other processes is negligible, and evapotranspiration is the main process for groundwater consumption. In addition, the information about diurnal water table fluctuations is useful for identification of groundwater-dependence of vegetation. A. ordosica is groundwater-independent, whereas S. psammophila is groundwater-dependent.

Cheng, Dong-hui; Li, Ying; Chen, Xunhong; Wang, Wen-ke; Hou, Guang-cai; Wang, Cun-liang

2013-05-01

62

High frequency sea level fluctuations recorded in the Black Sea since the LGM  

OpenAIRE

This paper presents a 3D geometric interpretation of very high resolution seismic Chirp profiles acquired on the Romanian shelf during ASSEMBLAGE European Project. The results provide a solid record of the Black Sea Last Glacial Maximum (LGM) water level fluctuations. This pseudo-3D seismic interpretation shows that the Black Sea lacustrine shelf deposits form a significant basinward-prograding wedge system. on top of these prograding sequences is a set of sand dunes that delineates a wave cu...

Lericolais, Gilles; Bulois, C.; Gillet, Herve; Guichard, F.

2009-01-01

63

A statistical approach to estimating evapotranspiration from diurnal groundwater level fluctuations  

Science.gov (United States)

Over the last few decades, automatic sensors that record groundwater levels at high-frequency intervals have become widely used in groundwater monitoring practice. These sensors provide large amounts of data regarding diurnal groundwater fluctuations, which can be treated as stochastic periodic time series. In this study, a simple relationship between the average standard deviation of diurnal groundwater level fluctuations and the daily evapotranspiration over relatively short periods (days or weeks) was developed for estimating groundwater consumption by phreatophytes in arid/semiarid areas. Our approach allows estimating groundwater evapotranspiration (ETg) using stable statistical characteristics of diurnal groundwater fluctuations, and it is useful for analyzing large amounts of data obtained from digital groundwater level monitoring sensors. A comparison of the ETg results from a synthetic set of groundwater level fluctuations with predefined values shows that this technique behaves consistently and is robust. A numerical analysis of one-dimensional saturated-unsaturated water flow to a root system using Richards' equation indicates that this method provides a reliable estimate of ETg when the basic assumptions of the White method are met. The method was also applied to two phreatophyte-dominated riparian sites in New Mexico to demonstrate its usefulness, which provides better results than the commonly used White method.

Wang, Ping; Pozdniakov, Sergey P.

2014-03-01

64

Characteristics of a Wire Level Sensor in the Measurement of a Free Surface Fluctuation  

International Nuclear Information System (INIS)

In the liquid metal reactor using sodium as a coolant, there exists a free surface in the upper plenum of the reactor vessel where the hot coolant contacts with a cold cover gas. The fluctuation of the free surface causes two important phenomena in the reactor. One is to induce a thermal stress to the reactor vessel due to the free surface fluctuation of sodium. Another is the cover gas entrainment at the free surface. If a significant amount of gas is entrained by the fluctuation of sodium, the entrained gas causes a change in the reactivity and also reduces the heat removal capability of the coolant in the core. Therefore it is an important parameter in the design of a liquid metal reactor. An experimental study will be carried out for measuring the fluctuating frequency and amplitude of the free surface in a cylindrical annular vessel where the inner vessel is simulated as a UIS of a reactor. Since the hydraulic property of sodium is similar to that of water, water is used as a working fluid instead of sodium. Because the range of the estimated frequency is about 0.5?5 Hz in this experiment, a conductivity type wire sensor is used as a level meter in order to get an accurate enough response. But the characteristic of this type level sensor have not been reported in the literature so far. Owing to this reason, an experiment is carried out to find the characteristics of the level sensor before the surface fluctuation measuring experiment. In the present paper the cg experiment. In the present paper the characteristics of the level sensor are described through an experiment

65

Dynamical Fluctuating Charge Force Fields Application to Liquid Water  

CERN Document Server

A new molecular dynamics model in which the point charges on atomic sites are allowed to fluctuate in response to the environment is developed and applied to water. The idea for treating charges as variables is based on the concept of electronegativity equalization according to which: (a) The electronegativity of an atomic site is dependent on the atom's type and charge and is perturbed by the electrostatic potential it experiences from its neighbors and (b) Charge is transferred between atomic sites in such a way that electronegativities are equalized. The charges are treated as dynamical variables using an extended Lagrangian method in which the charges are given a fictitious mass, velocities and kinetic energy and then propagated according to Newtonian mechanics along with the atomic degrees of freedom. Models for water with fluctuating charges are developed using the geometries of two common fixed-charge water potentials: the simple point charge (SPC) and the 4-point transferable intermolecular potential ...

Rick, S W; Berne, B J; Rick, Steven W.; Stuart, Steven J.

1994-01-01

66

Analyses of uncertainties and scaling of groundwater level fluctuations  

Science.gov (United States)

Analytical solutions for the variance, covariance, and spectrum of groundwater level, h(x, t), in an unconfined aquifer described by a linearized Boussinesq equation with random source/sink and initial and boundary conditions were derived. It was found that in a typical aquifer the error in h(x, t) in early time is mainly caused by the random initial condition and the error reduces as time progresses to reach a constant error in later time. The duration during which the effect of the random initial condition is significant may last a few hundred days in most aquifers. The constant error in h(x, t) in later time is due to the combined effects of the uncertainties in the source/sink and flux boundary: the closer to the flux boundary, the larger the error. The error caused by the uncertain head boundary is limited in a narrow zone near the boundary and remains more or less constant over time. The aquifer system behaves as a low-pass filter which filters out high-frequency noises and keeps low-frequency variations. Temporal scaling of groundwater level fluctuations exists in most part of a low permeable aquifer whose horizontal length is much larger than its thickness caused by the temporal fluctuations of areal source/sink.

Liang, X. Y.; Zhang, Y.-K.

2015-01-01

67

Mesoscale wind fluctuations over Danish waters  

DEFF Research Database (Denmark)

Mesoscale wind uctuations aect the large scale integration of wind power because they undermine the day-ahead predictability of wind speed and power production, and because they can result in large uctuations in power generation that must be balanced using reserve power. Large uctuations in generated power are a particular problem for oshore wind farms because the typically high concentration of turbines within a limited geographical area means that uctuations can be correlated across large numbers of turbines. Furthermore, organised mesoscale structures that often form over water, such as convective rolls and cellular convection, have length scales of tens of kilometers, and can cause large wind uctuations on a time scale of around an hour. This thesis is an exploration of the predictability of mesoscale wind uctuations using observations from the world's rst two large oshore wind farms - Horns Rev I in the North Sea, and Nysted in the Baltic Sea. The thesis begins with a climatological analysis of wind uctuations on time scales of 1{10 hours at the two sites. A novel method for calculating conditional climatologies of spectral information is proposed, based on binning and averaging the time axis of the Hilbert spectrum. Results reveal clear patterns between wind uctuations and locally observed meteorological conditions. The analysis is expanded by classifying wind uctuations on time scales of 1{3 hours according to synoptic patterns, satellite pictures and wind classes. Results indicate that cold air outbreaks and open cellular convection are a signicant contributor to mesoscale wind variability at Horns Rev. The predictability of mesoscale wind uctuations is tested by implementing standard statistical models that relate local wind variability to parameters based on a large scale weather analysis. The models show some skill, but only achieve a 15% improvement on a persistence forecast. The possibility of explicitly modelling mesoscale uctuations in a mesoscale model is then examined using the weatherresearch and forecasting (WRF) model. A set of case studies demonstrate that realistic hour-scale wind uctuations and open cellular convection patterns develop in WRF simulations with 2km horizontal grid spacing. The atmospheric conditions during one of the case studies are then used to initialise a simplied version of the model that has no large scale weather forcing, topography or surface inhomogeneties. Using the simplied model, the sensitivity of the modelled open cellular convection to choices in model setup and to aspects of the environmental forcing are tested. Finally, the cell-scale kinetic energy budget of the modelled cells is calculated, and it is shown that the buoyancy and pressure balance terms are important for cell maintenance. It is explained that the representation of mesoscale convection in a mesoscale model is not only important to end users such as wind farm operators, but to the treatment of energy transport within the boundary layer.

Vincent, Claire Louise

2010-01-01

68

Characterization of the level fluctuations in a physical model of the steel continuous casting mold through image processing  

Directory of Open Access Journals (Sweden)

configuration resembles a perfect control of the liquid level inside the water model. A high-speed video camera was used to get several video clips of the movement of the water level profile. Several techniques were tested in order to obtain the best lighting conditions for recording the water movement. The edge-detection technique of Sobel was used to determine the profile of the liquid level in each one of the images recorded. The analysis of the dynamic behavior of the water profile showed that the fluctuations of the liquid level inside the mold have a complex structure, which is repeated over large time periods.

J.R. Miranda-Tello

2012-01-01

69

Heterophase fluctuations and thermodynamic properties in supercooled water  

International Nuclear Information System (INIS)

On looking at the experimental findings on the thermodynamic properties of ordinary liquid water in supercooled state it is found that they can be consistently interpreted if a new contribution due to heterophase fluctuations is superimposed to a ''regular'' behaviour as given by a reliable extrapolation from the stable region. The ''monomer'' liquid which transforms into ice nuclei is associated with a ''close packed'' component of a two-state model interpreting the bulk medium extrapolated properties. By supposing that the amount of ice clusters depends on Tsub(M)-T, where Tsub(M) is the melting temperature, it is found that a simple relationship exists between the slope of the liquid-solid equilibrium curve and the heterophase fluctuation contributions to the isothermal compressibility and thermal-expansion coefficient. The consequences are discussed and compared with sound velocity experiments in water and with the behaviour of thermodynamic properties in other supercooled liquids. A substantial agreement is found

70

Estimation of evapotranspiration using diurnal groundwater level fluctuations: Comparison of different approaches with groundwater lysimeter data  

Science.gov (United States)

In wetlands or riparian areas, water withdrawal by plants with access to groundwater or the capillary fringe often causes diurnal groundwater fluctuations. Various approaches use the characteristics of these fluctuations for estimation of daily groundwater evapotranspiration rates. The objective of this paper was to review the available methods, compare them with measured evapotranspiration and assess their recharge assumptions. For this purpose, we employed data of 85 rain-free days of a weighable groundwater lysimeter situated at a grassland site in the Spreewald wetland in north-east Germany. Measurements of hourly recharge and daily evapotranspiration rates were used to assess the different approaches. Our results showed that a maximum of 50% of the day to day variance of the daily evapotranspiration rates could be explained by the approaches based on groundwater fluctuations. Simple and more complex methods performed similarly. For some of the approaches, there were indications that erroneous assumptions compensated each other (e.g., when overestimated recharge counteracted underestimated storage change). We found that the usage of longer time spans resulted in improved estimates of the daily recharge rates and that the estimates were further enhanced by including two night averages. When derived from fitting estimates of recharge or evapotranspiration with according measurements the specific yield, needed to convert changes in water level to water volumes, differed considerably among the methods (from 0.022 to 0.064). Thus, the specific yield can be seen as "correction factor" that compensates for inadequate process descriptions.

Fahle, Marcus; Dietrich, Ottfried

2014-01-01

71

Sea level rise and water storage on land  

Science.gov (United States)

Climate data was used to model the relationship between sea level rise and the loss of water stored in soils and snowpack on land. It was found that water stored on land did not make any lasting contribution to sea level rise during the 50 year period, although strong variation in precipitation and subsequent runoff, particularly in the tropics, caused sea level to fluctuate every ten years or so.

Duc et al.

72

Predicting groundwater level fluctuations with meteorological effect implications—A comparative study among soft computing techniques  

Science.gov (United States)

The knowledge of groundwater table fluctuations is important in agricultural lands as well as in the studies related to groundwater utilization and management levels. This paper investigates the abilities of Gene Expression Programming (GEP), Adaptive Neuro-Fuzzy Inference System (ANFIS), Artificial Neural Networks (ANN) and Support Vector Machine (SVM) techniques for groundwater level forecasting in following day up to 7-day prediction intervals. Several input combinations comprising water table level, rainfall and evapotranspiration values from Hongcheon Well station (South Korea), covering a period of eight years (2001-2008) were used to develop and test the applied models. The data from the first six years were used for developing (training) the applied models and the last two years data were reserved for testing. A comparison was also made between the forecasts provided by these models and the Auto-Regressive Moving Average (ARMA) technique. Based on the comparisons, it was found that the GEP models could be employed successfully in forecasting water table level fluctuations up to 7 days beyond data records.

Shiri, Jalal; Kisi, Ozgur; Yoon, Heesung; Lee, Kang-Kun; Hossein Nazemi, Amir

2013-07-01

73

Low level activity determination by means of gamma spectrometry with respect to the natural background fluctuation  

International Nuclear Information System (INIS)

The determination of low level activities of natural radionuclides from the uranium and thorium series by gamma-spectrometry faces the problem of proper natural background subtraction. Background fluctuation can cause differences in activity determination. Also the minimum detectable activity (MDA) of natural and artificial radionuclides can be influenced by background fluctuation. In this paper, results of the background fluctuation of shielded HPGe detectors with relative efficiency of 50–150% are presented together with the assessment of its influence on the determination of natural and artificial radionuclides. - Highlights: • Long term study of background peaks and integral counts. • Background fluctuation cause differences in low level activity determination. • Background fluctuation influence MDA calculation

74

Spectral diffusion in a fluctuating charge model of water  

OpenAIRE

We apply the combined electronic structure/molecular dynamics approach of Corcelli, Lawrence, and Skinner [J. Chem. Phys. 120, 8107 (2004)] to the fluctuating charge (SPC-FQ) model of liquid water developed by Rick, Stuart, and Berne [J. Chem. Phys. 101, 6141 (1994)]. For HOD in H2O the time scale for the long-time decay of the OD stretch frequency time-correlation function, which corresponds to the time scale for hydrogen-bond rearrangement in the liquid, is about 1.5 ps. This result is sign...

Corcelli, S. A.; Lawrence, C. P.; Asbury, J. B.; Steinel, T.; Fayer, M. D.; Skinner, J. L.

2004-01-01

75

Transfer Function Noise (TFN) Modeling of Dynamic Groundwater Level Fluctuation using Deseasonalized Rainfall Series  

Science.gov (United States)

A study to examine the effect of rainfall variable on groundwater level fluctuation was analyzed using transfer function noise (TFN) models for five representative wells from the study area of Adyar basin located in the north-east coastal part of Tamil Nadu, India. Five representative wells out of 43 were chosen based on maximum coefficient of determination (R2) value by simple linear regression analysis where rainfall and water level rise time series were used as independent and dependent variables respectively. An alternative method of zone wise Thiessen rainfall (ZTR), where the zones were separated by Thiessen method and the wells contained in the zones were regressed upon that particular zone station rainfall values with 100% weightage, was giving maximum R2 value compared to other traditional ways of estimating areal average rainfall methods such as simple arithmetic average (SAA) and Thiessen polygon (TP) methods. Water level fluctuation was further modeled using TFN modeling approach in which missing rainfall was filled using normal ratio (NR) method as it was giving maximum R2 value compared to simple station average (SSA) and inverse distance (ID) methods. A deseasonalized transfer function noise modeling (DS-TFN) approach has been adopted in the study which minimizes the number of numerator and denominator polynomial parameters and assures an improved method of forecasting groundwater level fluctuation in terms of maximum R2 and minimum root mean square error (RMSE) values compared to other traditional TFN models such as ARIMAX and SARIMAX. Before identifying suitable TFN model structure for input-output data, the data was analyzed for seasonality. Since both rainfall series and selected water level data show the seasonality behavior, it was adjusted with deseasonalizing process. Deseasonalizing process was carried out after detrending the data with 13-term moving average process and estimating seasonal component from the detrended series using seasonal indices. Deseasonalized data was then fitted with AR(1) model for both rainfall and water level series and the residual no serial correlation was verified with Ljung-Box Q-test. Pre-whitened residuals from both the series were stored and compared using cross correlation function (CCF). CCF for DS-TFN, ARIMAX and SARIMAX models show one month lag response of the input series over the output series for all 5 stations. ARIMAX and SARIMAX TFN model structure were identified using Box and Jenkins time series methodology where the best model was selected based on Akaike Information Criterion (AIC) values. Whereas DS-TFN model structure was identified with 1 numerator and 1 denominator polynomial coefficient which was enough to make the output residuals with white noise process that ultimately reduces the number of parameters for DS-TFN model.

Shanmugam, M.; Kumar, G.; Narasimhan, B.

2013-12-01

76

Studies on Diel Oxygen Fluctuation in a Tidal Brackish Water Farm at Ikoyi, Lagos, Nigeria  

Directory of Open Access Journals (Sweden)

Full Text Available This study provides baseline data on diel oxygen fluctuation in a tidal brackish water environment. Investigation on diel Dissolved Oxygen (DO fluctuation was carried out in a tidal brackish water habitat at two-hourly intervals in three ponds (6, 8 and 9. The highest mean dissolved oxygen values of 6.80, 7.00 and 3.90mg/1 for ponds 6, 8 and 9 respectively were recorded during the afternoon in the dry season. On the other hand, the lowest dissolved oxygen levels of 1.98, 3.00 and 0.20mg/1 for ponds, 6, 8 and 9 respectively were recorded during periods of heavy influx of suspended clay and silt particles in the peak of the rainy season. Analysis of Variance (ANOVA showed that DO values recorded during peak dry season were significantly higher (p?0.05 than those of the rainy season.

P.U. Uzukwu

2013-09-01

77

Structural Fluctuation of Protein in Water around Its Native State: A New Statistical Mechanics Formulation  

CERN Document Server

A new statistical mechanics formulation of characterizing the structural fluctuation of protein correlated with that of water is presented based on the generalized Langevin equation and the 3D-RISM/RISM theory of molecular liquids. The displacement vector of atom positions and their conjugated momentum, are chosen for the dynamic variables for protein, while the density fields of atoms and their momentum fields are chosen for water. Projection of other degrees of freedom onto those dynamic variables using the standard projection operator method produces essentially two equations which describe the time evolution of fluctuation concerning the density field of solvent and the conformation of protein around an equilibrium state, which are coupled with each other. The equation concerning the protein dynamics is formally akin to that of the coupled Langevin oscillators, and is a generalization of the latter, to atomic level. The most intriguing feature of the new equation is that it contains the variance-covarianc...

Kim, Bongsoo

2012-01-01

78

Investigation of free level fluctuations in a simulated model of a sodium cooled Fast Breeder Reactor using pulsating conductance monitoring device  

International Nuclear Information System (INIS)

Highlights: ? An innovative approach for measurement of water level fluctuation is presented. ? Measurement was conducted with a PC based pulsating type level sensor. ? Deployed the technique in monitoring level fluctuation in PFBR simulated facility. ? The technique helped in validation of hot pool design of PFBR, India. - Abstract: A high resolution measurement technique for rapid and accurate monitoring of water level using an in-house built pulsating conductance monitoring device is presented. The technique has the capability of online monitoring of any sudden shift in water level in a reservoir which is subjected to rapid fluctuations due to any external factor. We have deployed this novel technique for real time monitoring of water level fluctuations in a specially designed ¼ scale model of the Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, India. The water level measurements in various locations of the simulated test facility were carried out in different experimental campaigns with and without inclusion of thermal baffles to it in specific operating conditions as required by the reactor designers. The amplitudes and the frequencies of fluctuations with required statistical parameters in hot water pool of the simulated model were evaluated from the online time versus water level plot in more convenient way using system software package. From experimental results it is computed that the maximum free level fluctuation in the hot pool of PFBR with ban in the hot pool of PFBR with baffle plates provided on the inner vessel is 30 mm which is considerably less than the value (?82 mm) obtained without having any baffle plates. The present work provided useful information for assessment of appropriate design which would be adopted in the PFBR for safe operation of the reactor.

79

A field investigation of phreatophyte-induced fluctuations in the water table  

Science.gov (United States)

Hydrographs from shallow wells in vegetated riparian zones frequently display a distinctive pattern of diurnal water table fluctuations produced by variations in plant water use. A multisite investigation assessed the major controls on these fluctuations and the ecohydrologic insights that can be gleaned from them. Spatial and temporal variations in the amplitude of the fluctuations are primarily a function of variations in (1) the meteorological drivers of plant water use, (2) vegetation density, type, and vitality, and (3) the specific yield of sediments in the vicinity of the water table. Past hydrologic conditions experienced by the riparian zone vegetation, either in previous years or earlier within the same growing season, are also an important control. Diurnal water table fluctuations can be considered a diagnostic indicator of groundwater consumption by phreatophytes at most sites, so the information embedded within these fluctuations should be more widely exploited in ecohydrologic studies. Copyright 2007 by the American Geophysical Union.

Butler, J.J., Jr.; Kluitenberg, G.J.; Whittemore, D.O.; Loheide, S.P., II; Jin, W.; Billinger, M.A.; Zhan, X.

2007-01-01

80

Investigation of wall temperature fluctuations by visualization tests and numerical simulation for steam-water two-phase flow in the pressurizer spray piping  

International Nuclear Information System (INIS)

In a PWR plant, a steam-water two phase flow may possibly exist in the pressurizer spray pipe under a rated power operating condition since the flow rate of the spray water is not sufficient to fill the horizontal section of the pipe completely. Under such thermally stratified two phase flow conditions, the initiation of high cycle fatigue cracks is suspected to occur due to the cyclic thermal stress fluctuations caused by oscillations of the water surface, which cannot be detected by the measurement of temperature on outer surface of the pipe. In order to clarify the flow and thermal structure in the pressurizer spray pipe and assess its impact on the pipe structure, an experiment was conducted for a steam-water flow at a low flow rate in a simulated pressurizer spray piping. By measuring wall temperature fluctuations, continuous temperature fluctuations, which were around 0.2 times of the steam water temperature difference in the maximum range, were observed at the inclined section where the water surface contacted the pipe wall. So we planed to investigate the causes of the fluctuations by visualization tests. As a result of the experiment, it seemed that wall temperature fluctuations were not caused by waves on water surface, but caused by liquid temperature fluctuation in the layer below the steam-water interface. The influence of small amount of noncondensable gas dissolved in the reactor coolant on the wall temperature fluctuations was investigated by injectingfluctuations was investigated by injecting air into the experimental loop. Continuous water temperature fluctuations were attenuated after air was injected. A CFD analysis was performed adopting the VOF method for the experimental condition, and it successfully simulated the averaged temperature distribution but the level of water surface did not fluctuate, and no water temperature fluctuations below the gas-liquid interface were observed contrary to the experimental result. (author)

81

Reactor water level measuring device  

International Nuclear Information System (INIS)

A condensation vessel is connected to the upper portion of a reactor pressure vessel by way of a pipeline. The lower portion of the condensation vessel is connected to a low pressure side of a differential pressure transmission device by way of a reference leg pipeline. The high pressure side of the differential pressure transmission device is connected to the lower portion of the pressure vessel by way of a pipeline. The condensation vessel is equipped with a temperature sensor. When a temperature of a gas phase portion in the condensation vessel is lowered below a predetermined level, and incondensible gases in the condensation vessel starts to be dissolved in water, signals are sent from the temperature sensor to a control device and a control valve is opened. With such a constitution, CRD driving water flows into the condensation vessel, and water in which gases at the upper portion of the condensation vessel is dissolved flows into the pressure vessel by way of a pipeline. Then, gases dissolved in a reference water column in the reference leg pipeline are eliminated and the value of a reference water pressure does not change even upon abrupt lowering of pressure. (I.N.)

82

Fluctuations in sedation levels may contribute to delirium in ICU patients  

DEFF Research Database (Denmark)

Delirium in patients admitted to the intensive care unit (ICU) is a serious complication potentially increasing morbidity and mortality. The aim of this study was to investigate the impact of fluctuating sedation levels on the incidence of delirium in ICU.

Svenningsen, H; Egerod, Ingrid Eugenie

2013-01-01

83

Fluctuation properties of nuclear energy levels and widths: comparison of theory with experiment  

International Nuclear Information System (INIS)

We analyze the fluctuation properties of nuclear energy levels and widths with new spectrally averaged measures. A remarkably close agreement between the predictions of random-matrix theories and experiment is found

84

Method of controlling water level in reactor  

International Nuclear Information System (INIS)

Purpose: To enable continual retention of water level in a nuclear reactor to specified value. Method: When a water level in a reactor reaches a predetermined high-water-level setting point or low-water-level setting point, drain amount necessary for returning to an ordinary water level and drain amount necessary for maintaining the water level are calculated by a computer, the opening-degree of a drain control valve is calculated with a deviation between the drain amount thus calculated and the drain amount actually measured, thereby always maintaining the water level at the specified range. (Yoshihara, H.)

85

Memorization of short-range potential fluctuations in Landau levels  

International Nuclear Information System (INIS)

We calculate energy spectra of a two-dimensional electron system in a perpendicular magnetic field and periodic potentials of short periods. The Coulomb interaction is included within a screened Hartree-Fock approximation. The electrostatic screening is poor and the exchange interaction amplifies the energy dispersion. We obtain, by numerical iterations, self-consistent solutions that have a hysteresis-like property. With increasing amplitude of the external potential the energy dispersion and the electron density become periodic, and they remain stable when the external potential is reduced to zero. We explain this property in physical terms and speculate that a real system could memorize short-range potential fluctuations after the potential has been turned off. (author)

86

Effect of water table fluctuations on phreatophytic root distribution.  

Science.gov (United States)

The vertical root distribution of riparian vegetation plays a relevant role in soil water balance, in the partition of water fluxes into evaporation and transpiration, in the biogeochemistry of hyporheic corridors, in river morphodynamics evolution, and in bioengineering applications. The aim of this work is to assess the effect of the stochastic variability of the river level on the root distribution of phreatophytic plants. A function describing the vertical root profile has been analytically obtained by coupling a white shot noise representation of the river level variability to a description of the dynamics of root growth and decay. The root profile depends on easily determined parameters, linked to stream dynamics, vegetation and soil characteristics. The riparian vegetation of a river characterized by a high variability turns out to have a rooting system spread over larger depths, but with shallower mean root depths. In contrast, a lower river variability determines root profiles with higher mean root depths. PMID:25014476

Tron, Stefania; Laio, Francesco; Ridolfi, Luca

2014-11-01

87

An algorithm based on sea level pressure fluctuations to identify major Baltic inflow events  

Science.gov (United States)

The Baltic Sea is one of world largest brackish water areas with an estuarine like circulation. It is connected to the world ocean through the narrow Danish straits limiting the exchange of water masses. The deep water of the Baltic Sea is mainly renewed by so called major Baltic inflows which are an important feature to sustain the sensitive steady state of the Baltic Sea. We introduce an algorithm to identify atmospheric variability favourable for major Baltic inflows. The algorithm is based on sea level pressure fields as the only parameter. Characteristic sea level pressure pattern fluctuations include a precursory phase of 30 days and 10 days of inflow period. The algorithm identifies successfully the majority of observed major Baltic inflows between 1961--2010. In addition, the algorithm finds some occurrences which cannot be related to observed inflows. In these cases with favourable atmospheric conditions inflows were precluded by contemporaneously existing saline water masses or strong freshwater supply. No event is registered during the stagnation period 1983-1993 indicating that the lack of inflows is a consequence of missing favourable atmospheric variability. The only striking inflow which is not identified by the algorithm is the event in January 2003. We demonstrate that this is due to the special evolution of sea level pressure fields which are not comparable with any other event. Finally, the algorithm is applied to an ensemble of scenario simulations. The result indicates that the number of atmospheric events favourable for major Baltic inflows increases slightly in all scenarios. Possible explanations as for instance more frequent atmospheric blockings or changes in the NAO will be discussed.

Schimanke, Semjon; Dieterich, Christian; Markus Meier, H. E.

2014-05-01

88

The effect of pressurizer-water-level on the low frequency component of the pressure spectrum in a PWR  

International Nuclear Information System (INIS)

The pressure fluctuations were measured in the cooling system of the Paks-1 reactor. A shift of the peak was detected in low frequency component of the pressure fluctuation spectrum which is due to the fluctuations of water level in the pressurizer. Using the model of Katona and Nagy (1983), the eigenfrequencies, the magnitude of the shift and the sensitivity to the pressurizer water level were reproduced in good accordance with the experimental data. (D.Gy.)

89

Coherent sea-level fluctuations along the global continental slope  

OpenAIRE

Signals in sea-level or, more properly, sub-surface pressure (SSP; sea-level corrected for the inverse barometer effect) are expected to propagate rapidly along the continental slope due to the effect of sloping topography on wave modes, resulting in strongly correlated SSP over long-distances. Observations of such correlations around the Arctic and Antarctic are briefly reviewed, and then extended using satellite altimetry to the rest of the global continental slope. It is shown that such lo...

Hughes, Chris W.; Meredith, Michael P.

2006-01-01

90

Lake level fluctuations synchronize genetic divergences of cichlid fishes in African lakes.  

Science.gov (United States)

Water level fluctuations are important modulators of speciation processes in tropical lakes, in that they temporarily form or break down barriers to gene flow among adjacent populations and/or incipient species. Time estimates of the most recent major lowstands of the three African Great Lakes are thus crucial to infer the relative timescales of explosive speciation events in cichlid species flocks. Our approach combines geological evidence with genetic divergence data of cichlid fishes from the three Great East African Lakes derived from the fastest-evolving mtDNA segment. Thereby, we show for each of the three lakes that individuals sampled from several populations which are currently isolated by long geographic distances and/or deep water form clusters of equally closely related haplotypes. The distribution of identical or equally closely related haplotypes in a lake basin allows delineation of the extent of lake level fluctuations. Our data suggest that the same climatic phenomenon synchronized the onset of genetic divergence of lineages in all three species flocks, such that their most recent evolutionary history seems to be linked to the same external modulators of adaptive radiation. A calibration of the molecular clock of the control region was elaborated by gauging the age of the Lake Malawi species flock through the divergence among the utaka-cichlid and the mbuna-cichlid lineages to minimally 570,000 years and maximally 1 Myr. This suggests that the low-lake-level period which established the observed patterns of genetic relatedness dates back less than 57,000 years, probably even to 17,000-12,400 years ago, when Lake Victoria dried up and Lakes Malawi and Tanganyika were also low. A rapid rise of all three lakes about 11,000 years ago established the large-scale population subdivisions observed today. Over that period of time, a multitude of species originated in Lakes Malawi and Victoria with an impressive degree of morphological and ecological differentiation, whereas the Tanganyikan taxa that were exposed to the same habitat changes hardly diverged ecologically and morphologically. Our findings also show that patterns of genetic divergences of stenotopic organisms provide valuable feedback on geological and sedimentological time estimates for lake level changes. PMID:11158373

Sturmbauer, C; Baric, S; Salzburger, W; Rüber, L; Verheyen, E

2001-02-01

91

Monitoring device for reactor water level  

International Nuclear Information System (INIS)

Purpose: To improve the reliability in the reactor water level monitoring by estimating the reactor water level in an abnormal transient state and thereby forecast the water level response in a BWR type nuclear power plant. Constitution: Main process parameters (main steam flow rate, feedwater flow rate, reactor water level and reactor pressure) for a nuclear power plant are taken into an input device. An estimation device for actual reactor water level estimates an actual reactor water level based on these parameter data. If the detection range for a reactor water level detector is exceeded, it is judged by a judging device for reactor water level indication and the estimated value is employed for the monitoring of the reactor water level. The output from an estimation device for actual water level variation coefficient and an estimation value for actual reactor water level variation coefficient prepared by integrating the above output with time are inputted into a forecasting calculator for reactor water level response and the calculator outputs a forecast value for reactor water level response as a time function. (Seki, T.)

92

Stabilizing the domestic price level under fluctuating terms of trade  

OpenAIRE

In this paper a general equilibrium model of Chile will be applied to quantify (a) the requirements for real exchange rate stabilization in a commodity exporting country, (b) the implications of nominal exchange rate and price level stabilization, and (c) short-run benefits and long-run costs of using compensatory finance. The analysis will be done under conditions of both a closed and an open capital account. The recent Chilean experience, which will be sketched in chapter II, provides an al...

Gerken, Egbert

1983-01-01

93

Study on temperature fluctuation phenomena in pressurizer spray pipe of pressurized water reactor  

International Nuclear Information System (INIS)

Gas liquid inter is formed in a pressurizer spray pipe of a pressurized water reactor when flow rate is small at normal reactor operation. Temperature fluctuation may occur it the interface moves periodically. Measurement of inner wall and fluid temperature in the test section simulating the real pressurizer spray pipe was conducted to study mechanism of the temperature fluctuation phenomena. Experiments with and without non-condensable gas, air were conducted. The significant temperature fluctuation was not observed in air-water system and air-vapor-water system. The temperature fluctuation was observed in vapor-water system. Visualization was carried out at the horizontal part of the spray pipe. No interface movement was observed but vortices in the liquid layer near the interface were observed without non-condensable gas. It was estimated that Kelvin-Helmholtz instabilities occurred in the liquid layer near the interface. (author)

94

Sound fluctuations resulting from mode coupling in shallow-water internal waves  

Science.gov (United States)

We conduct a theoretical analysis and numerical simulation of fluctuations of low-frequency signals propagating in shallow water in the presence of nonlinear internal waves moving approximately along the acoustic track. It is believed that mode coupling causes the fluctuations. We show that in the fluctuation spectra there are characteristic frequencies that are proportional to the motion velocity of solitons along the track. We calculate the sound field using single- and multimode sources and analyze the frequency-mode composition of the field responsible for the maximum and minimum fluctuations. We analyze the so-called dominant fluctuation frequency introduced previously by the authors, which corresponds to fluctuations with the maximum amplitude in the given frequency range and for the given set of modes. We compare the calculation results with estimates obtained previously by the authors within the framework of ray theory.

Grigor'ev, V. A.; Katsnel'son, B. G.

2014-05-01

95

Characterization of the level fluctuations in a physical model of the steel continuous casting mold through image processing  

Scientific Electronic Library Online (English)

Full Text Available In this work is characterized the periodic behavior of the liquid level inside a scaled cold-model of the mold section of a steel continuous casting machine, which uses water as working fluid. The models are designed in order to simulate the dynamic forces acting on the molten steel inside a mold of [...] continuous casting. The force magnitude can induce choppy flow, waves and vortex formation in the mold. The experimental model uses a closed-loop hydraulic configuration. In the mold, the inlet and the outlet water flow rates are the same. This configuration resembles a perfect control of the liquid level inside the water model. A high-speed video camera was used to get several video clips of the movement of the water level profile. Several techniques were tested in order to obtain the best lighting conditions for recording the water movement. The edge-detection technique of Sobel was used to determine the profile of the liquid level in each one of the images recorded. The analysis of the dynamic behavior of the water profile showed that the fluctuations of the liquid level inside the mold have a complex structure, which is repeated over large time periods.

J.R., Miranda-Tello; F., Sánchez-Rangel; C.A., Real-Ramírez; G., Khatchatourov; J.A., Aragón-Lezama; L.F., Hoyos-Reyes; E.A., Andrade-González; J.I., González-Trejo.

2012-04-01

96

Coherent sea-level fluctuations along the global continental slope.  

Science.gov (United States)

Signals in sea-level or, more properly, sub-surface pressure (SSP; sea-level corrected for the inverse barometer effect) are expected to propagate rapidly along the continental slope due to the effect of sloping topography on wave modes, resulting in strongly correlated SSP over long-distances. Observations of such correlations around the Arctic and Antarctic are briefly reviewed, and then extended using satellite altimetry to the rest of the global continental slope. It is shown that such long-distance correlations are common, especially in extra-tropical regions. Simple correlations from altimetry cannot, however, establish the wave speed, or whether waves are responsible for the correlations as opposed to large-scale coherence in the forcing. A case study around South America is used to highlight some of the complications, and is found to strengthen the case for the importance of wave modes in such long-distance SSP coherence, although more detailed in situ data are required to resolve the cause of the correlations. PMID:16537146

Hughes, Chris W; Meredith, Michael P

2006-04-15

97

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

Science.gov (United States)

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 between the stable and fluctuating water table columns were detected.

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

2014-02-01

98

Does temperature affect the accuracy of vented pressure transducer in fine-scale water level measurement?  

Science.gov (United States)

Submersible pressure transducers have been utilized for collecting water level data since the early 1960s. Together with a digital data logger, it is a convenient way to record water level fluctuations for long-term monitoring. Despite the wide use of pressure transducers for water level monitoring, little has been reported regarding their accuracy and performance under field conditions. The effects of temperature fluctuations on the output of vented pressure transducers were considered in this study. The pressure transducers were tested under both laboratory and field conditions. The results of this study indicate that temperature fluctuation has a strong effect on the transducer output. Rapid changes in temperature introduce noise and fluctuations in the water level readings under a constant hydraulic head while the absolute temperature is also related to sensor errors. The former is attributed to venting and the latter is attributed to temperature compensation effects in the strain gauges. Individual pressure transducers responded differently to the thermal fluctuations in the same testing environment. In the field of surface hydrology, especially when monitoring fine-scale water level fluctuations, ignoring or failing to compensate for the temperature effect can introduce considerable error into pressure transducer readings. It is recommended that a performance test for the pressure transducer is conducted before field deployment.

Liu, Z.; Higgins, C. W.

2015-03-01

99

Ground Water Level Measurements in Selected Boreholes Near the Site of the Proposed Repository  

Energy Technology Data Exchange (ETDEWEB)

The Harry Reid Center for Environmental Studies (HRC) at the University of Nevada, Las Vegas (UNLV) acquired quarterly and continuous data on water levels from approximately 26 boreholes that comprise a periodic monitoring network (Table 1) between October 2003 and September 2007. During this period we continued to observe and analyze short and long-term ground water level trends in periodically monitored boreholes. In this report we summarize and discuss four key findings derived from analysis of water level data acquired during this period: 1. Rapid ground water level rise after storm events in Forty Mile Canyon; 2. Seismically-induced ground water level fluctuations; 3. A sample of synoptic observations and barometric influences on short term fluctuations; and 4. Long term ground water level trends observed from mid-2001 through late-2005.

Page, H. Scott

2007-11-29

100

Development of Mechanical Water Level Controller  

OpenAIRE

The automatic water level controller is a device designed to regulate automatically the pumping of water to an overhead tank without allowing the water in the tank to be exhausted. The design of this mechanical device was achieved using the Archimedes principle of floatation; having a float which determines the water level in the tank depending on the choice of the minimum (lower) and maximum (upper) level inscribed in the tank. The fundamental attribute of this device is the ease in design, ...

Akonyi Nasiru Sule; Chinedu Cletus Obinwa; Christian Ebele Okekeze; Eyo Ifreke

2012-01-01

101

Analysis of water levels in the Frenchman Flat area, Nevada Test Site  

Science.gov (United States)

Analysis of water levels in 21 wells in the Frenchman Flat area, Nevada Test Site, provides information on the accuracy of hydraulic-head calculations, temporal water-level trends, and potential causes of water-level fluctuations. Accurate hydraulic heads are particularly important in Frenchman Flat where the hydraulic gradients are relatively flat (less than 1 foot per mile) in the alluvial aquifer. Temporal water-level trends with magnitudes near or exceeding the regional hydraulic gradient may have a substantial effect on ground-water flow directions. Water-level measurements can be adjusted for the effects of barometric pressure, formation water density (from water-temperature measurements), borehole deviation, and land-surface altitude in selected wells in the Frenchman Flat area. Water levels in one well were adjusted for the effect of density; this adjustment was significantly greater (about 17 feet) than the adjustment of water levels for barometric pressure, borehole deviation, or land-surface altitude (less than about 4 feet). Water-level measurements from five wells exhibited trends that were statistically and hydrologically significant. Statistically significant water-level trends were observed for three wells completed in the alluvial aquifer (WW-5a, UE-5n, and PW-3), for one well completed in the carbonate aquifer (SM-23), and for one well completed in the quartzite confining unit (Army-6a). Potential causes of water-level fluctuations in wells in the Frenchman Flat area include changes in atmospheric conditions (precipitation and barometric pressure), Earth tides, seismic activity, past underground nuclear testing, and nearby pumping. Periodic water-level measurements in some wells completed in the carbonate aquifer indicate cyclic-type water-level fluctuations that generally correlate with longer term changes (more than 5 years) in precipitation. Ground-water pumping fromthe alluvial aquifer at well WW-5c and pumping and discharge from well RNM-2s appear to cause water-level fluctuations in nearby observation wells. The remaining known sources of water-level fluctuations do not appear to substantially affect water-level changes (seismic activity and underground nuclear testing) or do not affect changes over a period of more than 1 year (barometric pressure and Earth tides) in wells in the Frenchman Flat area.

Bright, D.J.; Watkins, S.A.; Lisle, B.A.

2001-01-01

102

Water level detector for BWR type reactor  

International Nuclear Information System (INIS)

Purpose: To accurately detect the water level of reactor irrespective of the reactor water flow velocity. Constitution: A total pressure detecting port is opened at the upstream side of the reactor water flowing direction in a BWR type reactor, and the water level is detected from the differential pressure between the total pressure detected at the total pressure detecting port and a reference head pressure. Or, a total pressure detecting port and a static pressure detecting port are provided, static and dynamic pressures are thus separately detected, converted into electric signals, corrected and added, a signal corresponding to the differential pressure between the total pressure and the reference head pressure is thus obtained, and the water level is detected with the signal. Accordingly, the water level can be accurately obtained regardless of the reactor water flow velocity, the dynamic pressure having a relatively large error can be corrected, and the water level can be detected more accurately. (Yoshihara, H.)

103

Water level measurement uncertainty during BWR instability  

Energy Technology Data Exchange (ETDEWEB)

This paper addresses the performance of the water-level measurement system in a boiling water reactor (BWR) during severe instability oscillations which, under some circumstances, can occur during an anticipated transient without SCRAM (ATWS). Test data from a prototypical mock-up of the water-level measurement system was used to refine and calibrate a water-level measurement system model. The model was then used to predict level measurement system response, using as boundary conditions vessel pressures calculated by RETRAN for an ATWS/instability event.The results of the study indicate that rapid pressure changes in the reactor pressure vessel which cause oscillations in downcomer water level, coupled with differences in instrument line lengths, can produce errors in the sensed water level. Using nominal parameters for the measurement system components, a severe instability transient which produced a 0.2 m peak-to-minimum water-level oscillation in the vessel downcomer was predicted to produce pressure difference equivalent to a 0.7 m level oscillation at the input to the differential pressure transmitter, 0.5 m oscillation at the output of the transmitter, and an oscillation of 0.3 m on the water-level indicator in the control room. The level measurement system error, caused by downcomer water-level oscillations and instrument line length differential, is mitigated by damping both in the differential pressure transmitter used to infer level and in the control room display instrument. ((orig.))

Torok, R.C. (Electric Power Research Institute, PO Box 10412, Palo Alto, CA 94303 (United States)); Derbidge, T.C. (The Research Partnership, 814 Henrietta Avenue, Sunnyvale, CA 94086 (United States)); Healzer, J.M. (S. Levy Incorporated, 3425 South Bascom Avenue, Campbell, CA 95008-7006 (United States))

1994-11-15

104

Quantum chaos: spectral fluctuations and overlap distributions of the three level Lipkin-Meshkov-Glick model  

International Nuclear Information System (INIS)

The author test the prediction that quantum systems with chaotic classical analogs have spectral fluctuations and overlap distributions equal to those of the Gaussian Orthogonal Ensemble (GOE). The subject of our study is the three level Lipkin-Meshkov-Glick model of nuclear physics. This model differs from previously investigated systems because the quantum basis and classical phase space are compact, and the classical Hamiltonian has quartic momentum dependence. We investigate the dynamics of the classical analog to identify values of coupling strength and energy ranges for which the motion is chaotic, quasi-chaotic, and quasi-integrable. We then analyze the fluctuation properties of the eigenvalues for those same energy ranges and coupling strength, and we find that the chaotic eigenvalues are in good agreement with GOE fluctuations, while the quasi-integrable and quasi-chaotic levels fluctuations are closer to the Poisson fluctuations that are predicted for integrable systems. We also study the distribution of the overlap of a chaotic eigenvector with a basis vector, and find that in some cases it is a Gaussian random variable as predicted by GOE. This result, however, is not universal

105

Water level indicator for nuclear reactor  

International Nuclear Information System (INIS)

Purpose: To correctly indicate the water level in a reactor under all operating conditions by correcting the apparent decrease in the indication of a wide range water level indicator due to flow rate in the reactor core and apparent variations in the indication of the wide range water level indicator due to subcooling of the feedwater. Constitution: The water level signal of a wide range water level indicator is corrected in accordance with a flow rate correction signal and a subcooling correction signal by a water level deviation correcting adder, so the water level indicator will thus produce an actual water level signal, preferably matched with the indication of a narrow range water level indicator, to a wide range corrected water level indicator. The flow rate correction signal is obtained as an output signal of a function generator to which a reactor core flow rate signal is input and which incorporates a reactor core flow rate correction function. Further, the subcooling correction signal is obtained as an output signal of a function generator to which the temperature difference signal of a pump inlet temperature signal and a main steam temperature signal are input, and which also incorporates a subcooling correction function. (Yoshino, Y.)

106

Changes in climate, catchment vegetation and hydrogeology as the causes of dramatic lake-level fluctuations in the Kurtna Lake District, NE Estonia  

Directory of Open Access Journals (Sweden)

Full Text Available Numerous lakes in the world serve as sensitive indicators of climate change. Water levels for lakes Ahnejärv and Martiska, two vulnerable oligotrophic closed-basin lakes on sandy plains in northeastern Estonia, fell more than 3 m in 1946–1987 and rose up to 2 m by 2009. Earlier studies indicated that changes in rates of groundwater abstraction were primarily responsible for the changes, but scientifically sound explanations for water-level fluctuations were still lacking. Despite the inconsistent water-level dataset, we were able to assess the importance of changing climate, catchment vegetation and hydrogeology in water-level fluctuations in these lakes. Our results from water-balance simulations indicate that before the initiation of ground­water abstraction in 1972 a change in the vegetation composition on the catchments triggered the lake-level decrease. The water-level rise in 1990–2009 was caused, in addition to the reduction of groundwater abstraction rates, by increased precipitation and decreased evaporation. The results stress that climate, catchment vegetation and hydrogeology must all be considered while evaluating the causes of modern water-level changes in lakes.

Marko Vainu

2014-02-01

107

NOAA: About Water Levels, Tides and Currents  

Science.gov (United States)

A comprehensive lesson on what causes tides, current and past techniques for predicting tides, how and why water level is measured, and the challenges of measuring water currents. Site provides additional links to other NOAA tide resources.

108

Solute Transport Under Water Table Fluctuations in a Fine Sand and a Sandy Clay Loam Soil  

Directory of Open Access Journals (Sweden)

Full Text Available Drainage contributes to removing the excess of water from cultivated land. In general, most common drainage systems lead to loss of fertilizers applied for plant growth and yield improvement. Thus, the main objective of this work was to study experimentally the redistribution of solutes within the soil profile caused by water table fluctuations by making use of a non-reactive tracer in laboratory studies on soil columns. Two soil materials, namely fine sand and a sandy clay loam soil, were used in this study. Use was made of potassium chloride as a non-reactive tracer. Profiles of chloride redistribution as a function of depth caused by a first drainage of a saturated column with chloride in the surface layer, sub-irrigation and a second drainage were obtained for the fine sand columns with draining water levels at depths 25.5 and 44.5 cm, and for the sandy clay loam columns with a draining water level at depth 44.5 cm. Although only results for water table depth at 44.5 cm for both soils materials are presented. The redistribution of chloride in both the fine sand and the sandy clay loam columns was dominantly attributed to convective movement of solutes and was considered to be little influenced by diffusion. Preferential flow could have taken place through large sized pores of the fine sand columns. The knowledge and data of this study is a contribution towards that needed to define operation strategies for sub-irrigation-drainage systems which can lead to optimize fertilizers use by crops.

Cesáreo Landeros-Sánchez

2013-12-01

109

Measuring water level in a steam generator  

International Nuclear Information System (INIS)

A method is provided for determining and controlling steam water level in a steam generator of a nuclear plant, comprising calibrating the water level sensor in terms of velocity head and also adjusting the high level setpoint in terms of a velocity head bias. The water level differential pressure sensor is calibrated so that maximum water level is indicated as that level corresponding to the upper tap level less velocity head at maximum power plant power. The high level set point is calculated as corresponding to the riser level less a velocity head bias in flow path, the bias being calculated as maximum velocity head at maximum velocity minus rider head percentage of span times velocity head at maximum power. (author)

110

Ground-water levels in water year 1987 and estimated ground-water pumpage in water years 1986-87, Carson Valley, Douglas County, Nevada  

Science.gov (United States)

Groundwater levels were measured at 58 wells during water year 1987 and a summary of estimated pumpage is given for water years 1986 and 1987 in Carson Valley, Douglas County, Nevada. The data were collected to provide a record of groundwater changes over the long-term and pumpage estimates that can be incorporated into an existing groundwater model. The estimated total pumpage in water year 1986 was 10,200 acre-ft and in water year 1987 was 13,400 acre-ft. Groundwater levels exhibited seasonal fluctuations but remained relatively stable over the reporting period throughout most of the valley. (USGS)

Berger, D.L.

1990-01-01

111

Understanding connected surface-water/groundwater systems using Fourier analysis of daily and sub-daily head fluctuations  

Science.gov (United States)

The long-term monitoring records of hydraulic heads frequently contain fluctuations originating from different cyclic drivers. Fourier analysis applied to these records can reveal connected surface-water/groundwater system characteristics. The various components of the atmospheric tides, the earth tides and the presence of diurnal responses to evapotranspiration are identified and isolated through band-pass filtering of data recorded from both vented and absolute gauge transducers. The signature of the different cyclic drivers is contained in amplitude and phase of the various signal components and can be used to determine the degree of system confinement. A methodology is described for the calculation of barometric efficiency in confined aquifers based upon the amplitude of the M2 and S2 components of the earth and atmospheric tides. It is demonstrated that Fourier analysis of water-level fluctuations is a simple but underused tool that can help to characterise shallow groundwater systems.

Acworth, R. I.; Rau, Gabriel C.; McCallum, Andrew M.; Andersen, Martin S.; Cuthbert, Mark O.

2015-02-01

112

Calculated yields and fluctuations for electron degradation in liquid water and water vapor  

International Nuclear Information System (INIS)

Two sets of physical interaction cross sections for detailed electron track-structure calculations in liquid water and water vapor have been used to investigate the possible magnitude of phase-dependent differences in the primary yields of ionizations and their fluctuations produced during complete slowing down of electrons in the energy range from 10 eV to 10 keV. For fast electrons the calculated values of the mean energy absorbed per ion pair are 25.8 eV/ip for the liquid as compared to 30.0 eV/ip for the vapor; both results are consistent with experimental data. A similar phase effect is found in the ionization yields from each molecular subshell, since essentially the same partitioning of the total ionization cross section has been used in the calculations for the liquid and the vapor. The relative fluctuations of the ionization yields as described by the Fano factor are 0.15 for the liquid and 0.25 for the vapor; the Fano factors for each single molecular orbital are typically between 0.7 and 0.9 in both phases. The distributions in the total number of ionizations produced by the complete slowing down of electrons with initial energies above about 100 eV are Gaussian within about two standard deviations around the mean. The significance of the differences in the yields of ionizations and excitations calculated for both phases is discussed. In the absence of adequate experimental data for the basic processes, the differences are interpreted in terms of the respecces are interpreted in terms of the respective assumptions made for single scattering processes

113

Water Table Fluctuation in Tidal Lowland for Developing Agricultural Water Management Strategies  

Directory of Open Access Journals (Sweden)

Full Text Available The research objective is to evaluate the water status in the tertiary block of tidal lowland for developing water management strategies and cropping pattern for food crop agriculture. The research was conducted in tidal lowland reclamation areas of Delta Saleh South Sumatera. The methodology used in this research was survey and monitoring. The result showed that the study area has a potential of acid sulphate soil which is indicated by phyrite layer at 60 cm below the soil surface. Variation of water table was very high in the range of 0-2 cm at rainy season and it was drop up to 90 to 100 cm below soil surface at dry season. This conditions result in the soil oxidation and the pH drop up to 2.5-3.5 (very acid. Analysis of water surplus and deficit during one year period was calculated by surplus excess water under 30 cm (SEW-30 and showed that the area study was experienced water deficit. Analysis of groundwater effect on soil moisture content showed that the critical water level was in 60 cm below soil surface. The soil moisture content at this point in the root zone was dropped into the wilting point level. It means that the water availability for crop water requirement is inadequate. For sustainable agriculture in the area study, the water table should be maintained in 50-60 cm below soil surface. Therefore, the recommendation of water management strategies in the study area is water retention in combination with control drainage system.

Momon Sodik Imanudin

2010-09-01

114

Periodic fluctuations in deep water formation due to sea ice  

CERN Document Server

During the last ice age several quasi-periodic abrupt warming events took place. Known as Dansgaard-Oeschger (DO) events their effects were felt globally, although the North Atlantic experienced the largest temperature anomalies. Paleoclimate data shows that the fluctuations often occurred right after massive glacial meltwater releases in the North Atlantic and in bursts of three or four with progressively decreasing strengths. In this study a simple dynamical model of an overturning circulation and sea ice is developed with the goal of understanding the fundamental mechanisms that could have caused the DO events. Interaction between sea ice and the overturning circulation in the model produces self-sustained oscillations. Analysis and numerical experiments reveal that the insulating effect of sea ice causes the ocean to periodically vent out accumulated heat in the deep ocean into the atmosphere. Subjecting the model to idealized freshwater forcing mimicking Heinrich events causes modulation of the natural p...

Saha, Raj

2015-01-01

115

Effects of water compressibility on the pressure fluctuation prediction in pump turbine  

International Nuclear Information System (INIS)

The compressible effect of water is a key factor in transient flows. However, it is always neglected in the unsteady simulations for hydraulic machinery. In light of this, the governing equation of the flow is deduced to combine the compressibility of water, and then simulations with compressible and incompressible considerations to the typical unsteady flow phenomenon (Rotor stator interaction) in a pump turbine model are carried out and compared with each other. The results show that water compressibility has great effects on the magnitude and frequency of pressure fluctuation. As the operating condition concerned, the compressibility of water will induce larger pressure fluctuation, which agrees better with measured data. Moreover, the lower frequency component of the pressure signal can only be captured with the combination of water compressibility. It can be concluded that water compressibility is a fatal factor, which cannot be neglected in the unsteady simulations for pump turbines.

116

Effects of water compressibility on the pressure fluctuation prediction in pump turbine  

Science.gov (United States)

The compressible effect of water is a key factor in transient flows. However, it is always neglected in the unsteady simulations for hydraulic machinery. In light of this, the governing equation of the flow is deduced to combine the compressibility of water, and then simulations with compressible and incompressible considerations to the typical unsteady flow phenomenon (Rotor stator interaction) in a pump turbine model are carried out and compared with each other. The results show that water compressibility has great effects on the magnitude and frequency of pressure fluctuation. As the operating condition concerned, the compressibility of water will induce larger pressure fluctuation, which agrees better with measured data. Moreover, the lower frequency component of the pressure signal can only be captured with the combination of water compressibility. It can be concluded that water compressibility is a fatal factor, which cannot be neglected in the unsteady simulations for pump turbines.

Yin, J. L.; Wang, D. Z.; Wang, L. Q.; Wu, Y. L.; Wei, X. Z.

2012-11-01

117

Analysis on the characteristics of parameters in groundwater table fluctuation model for predicting groundwater levels in Hancheon watershed, South Korea  

Science.gov (United States)

A novel application of groundwater table fluctuation method is suggested to predict groundwater level by means of groundwater table variation due to recharge and discharge under unsteady condition. This model analyzes transient groundwater characteristics by using reaction factor related with groundwater flow and specific yield related with recharge. The groundwater level varies according to the characteristics and composite materials of aquifer. In this study, specific yield and reaction factor which are the major two hydrogeological parameters in the WTF(Water Table Fluctuation) method were estimated and analyzed their spatial characteristics. 8 groundwater level stations which have enough measuring period and high correlation with rainfall in the Hancheon watershed were used. The results showed that specific yield was randomly distributed and reaction factor showed inverse trend with altitude. If the enough data were collected, reaction factor according to altitude in ungauged points could be estimated by using these parameter characteristics. keywords: Key words : Groundwater level, parameters, reaction factor, specific yield Acknowledgements This research was supported by the Regional Innovative Technology Project 2B from KICTTEP.

Kim, Nam Won; Kim, Youn Jung; Chung, Il-Moon; Lee, Jeongwoo

2014-05-01

118

Effect of changes in water level on sediment pore water redox geochemistry at a reservoir shoreline  

International Nuclear Information System (INIS)

Research highlights: ? Initially, reducing conditions existed in pore water of submerged shoreline sediment. ? Exposure of sediment to air by falling water level appears to have oxidized the sediment. ? Re-submergence of sediment led to reducing conditions in pore water after <5 days in one location. ? Pore water manganese and uranium generally show opposite trends in response to redox conditions. - Abstract: Pore water samplers with high vertical resolution were used to evaluate the response of sediment redox geochemistry during transient hydrologic conditions at Lake Powell, a large reservoir in Utah and Arizona, USA. Samplers were deployed at two different yet proximal shoreline locations, White and Farley Canyons, before and after exposure of sediment to air and subsequent resubmersion, which resulted from fluctuations in the water level of the reservoir. Before exposure to air, an observed increase in dissolved Mn concentrations and, at Farley Canyon, an observed decrease in dissolved U concentrations across and immediately below the sediment-water interface indicated reducing conditions in the sub-surface. After exposure and resubmersion of the sediment, pore water profiles at each site differed distinctly from those observed before the fluctuation in water level. At White Canyon, an increase in U concentrations and a decrease in Mn concentrations in pore water after exposure and subsequent resubmersion are suggestive of oxidative processes occurring dur oxidative processes occurring during the period of sediment exposure. Data from Farley Canyon suggest that the same processes may be occurring, but to a lesser extent. Depth profiles of As and Pb were also examined, but were relatively featureless compared to those of Mn and U. At both sites, sediment evaluated for pore water chemistry in the second sampling was only fully resubmerged for 2-5 days prior to the second sampling event, yet reducing conditions were clearly evident in the Mn pore water profiles. This suggests that the dynamics of the biogeochemical processes occurring in surface sediment at Lake Powell are responsive on the timescale defined by the fluctuating water levels in the reservoir.

119

Water level measurement uncertainty during BWR instability  

International Nuclear Information System (INIS)

This paper addresses the performance of the water-level measurement system in a boiling water reactor (BWR) during severe instability oscillations which, under some circumstances, can occur during an anticipated transient without SCRAM (ATWS). Test data from a prototypical mock-up of the water-level measurement system was used to refine and calibrate a water-level measurement system model. The model was then used to predict level measurement system response, using as boundary conditions vessel pressures calculated by ppercase RETRAN for an ATWS/instability event.The results of the study indicate that rapid pressure changes in the reactor pressure vessel which cause oscillations in downcomer water level, coupled with differences in instrument line lengths, can produce errors in the sensed water level. Using nominal parameters for the measurement system components, a severe instability transient which produced a 0.2 m peak-to-minimum water-level oscillation in the vessel downcomer was predicted to produce pressure difference equivalent to a 0.7 m level oscillation at the input to the differential pressure transmitter, 0.5 m oscillation at the output of the transmitter, and an oscillation of 0.3 m on the water-level indicator in the control room. The level measurement system error, caused by downcomer water-level oscillations and instrument line length differential, is mitigated by damping both in the differential pressure transmitter used to infer level and in the contritter used to infer level and in the control room display instrument. ((orig.))

120

The fluctuating political appeal of water engineering in Australia  

OpenAIRE

Like many nations, Australia has a mixed history with water engineering. For over a century the engineer was 'king' and water was harnessed as a vehicle for settling the harsh inland, creating wealth and building prosperity. By the 1960s it was becoming increasingly clear that this approach was not without its flaws. Mounting evidence of environmental degradation emerged in the 1970s and the trend towards fiscal responsibility in the 1980s subjected the engineering approach to even greater sc...

Crase, Lin R.; O’keefe, Suzanne M.; Dollery, Brian E.

2009-01-01

121

Development of Mechanical Water Level Controller  

Directory of Open Access Journals (Sweden)

Full Text Available The automatic water level controller is a device designed to regulate automatically the pumping of water to an overhead tank without allowing the water in the tank to be exhausted. The design of this mechanical device was achieved using the Archimedes principle of floatation; having a float which determines the water level in the tank depending on the choice of the minimum (lower and maximum (upper level inscribed in the tank. The fundamental attribute of this device is the ease in design, fabrication and mounting at a lower cost. Its testing had shown and proved that it works efficiently with Archimedes’ principle of floatation. This eliminates the frequent human intervention/monitoring of the water level in the overhead tank to control overflow manually, thereby eliminating water and energy wastages.

Akonyi Nasiru Sule

2012-10-01

122

Method for steam generator water level measurement  

International Nuclear Information System (INIS)

This paper describes a nuclear power plant, a method of controlling the steam generator water level, wherein the steam generator has an upper level tap corresponding to an upper level, a lower level, a riser positioned between the lower and upper taps, and level sensor means for indicating water level between a first range limit and a second range limit, the sensor means being connected to at least the lower tap. It comprises: calculating a measure of velocity head at about the lower level tap; calculating a measure of full water level as the upper level less the measure of velocity head; calibrating the level sensor means to provide an output at the first limit corresponding to an input thereto representative of the measure of full level; calculating a high level setpoint equal to the level of the riser less a bias amount which is a function of the position of the riser relative to the span between the taps; and controlling the water level when the sensor means indicates that the high level setpoint has been reached

123

Water-table fluctuations in the Amargosa Desert, Nye County, Nevada  

International Nuclear Information System (INIS)

Pleistocene ground-water discharge deposits approximately 20 km southwest of Yucca Mountain were previously thought to represent pluvial water-table rises of 80 to 120 m. Data from new boreholes at two of the three discharge sites indicate that the modern water-table is at depths of only 17 to 30 m and that this shallow water is part of the regional ground-water flow system rather than being perched. Calcite in equilibrium with this modern ground water would have isotopic compositions similar to those in Pleistocene calcite associated with the discharge deposits. Carbon and uranium isotopes in both ground water and discharge deposits imply that past discharge consisted of a mixture of both shallow and deep ground water. These data limit Pleistocene water-table fluctuations at the specified Amargosa Desert discharge sites to between 17 and 30 m and eliminate the need to invoke large water-table rises

124

Shallow Water Internal Waves and Associated Acoustic Intensity Fluctuations  

Directory of Open Access Journals (Sweden)

Full Text Available Physical oceanographic and acoustic data were simultaneously collected from the coastalwaters of the Arabian Sea. Acoustic transmissions were carried out from an anchored vesselusing 620 Hz transducer and received by an array of hydrophones moored at ~5 km away fromthe anchorage. Thermal structure in this region was characterised by a tri-layer structure, ie, astrong thermocline (> 0.4 oC/m sandwiched between an upper (< 10 m and bottom (> 25 mhomogeneous layer. High-resolution (sampled at 10 s interval temperature data from mooredsensors revealed intense internal wave activity. The maximum value of Brunt-Vaisala frequency,which is the maximum frequency limit of internal waves in the thermocline, suggests that theupper frequency limit of the internal wave, which can be generated during this period, is 23 cph(2.6 min. High and low frequency waves caused variations of ~3 oC and ~5 oC respectively inthe temperature field. But the low frequency internal waves were found to contain maximumenergy compared to the high frequency waves. Fluctuations of 8-12 dB were noticed in themeasured acoustic intensity values in the presence of low frequency internal waves. Simulationstudies carried out using parabolic equation model using 620 Hz source indicated well-definedducted propagation with minimum transmission loss, when the source was kept within thehomogeneous layer. The presence of tri-layer thermal structure, ie, a strong gradient layersandwiched between an upper and bottom homogeneous layer, caused surface and bottom channelpropagation in this region.

P.V. Hareesh Kumar

2006-10-01

125

Magnetization reversal and two level fluctuations by spin-injection in a ferromagnetic metallic layer  

OpenAIRE

Slow magnetic relaxation and two level fluctuations measurements under high current injection is performed in single-contacted ferromagnetic nanostructures. The magnetic configurations of the samples are described by two metastable states of the uniform magnetization. The current-dependent effective energy barrier due to spin-transfer from the current to the magnetic layer is measured. The comparison between the results obtained with Ni nanowires of 6 $\\mu $m length and 60 n...

Wegrowe, J. -e

2003-01-01

126

Water level control device for nuclear reactor  

International Nuclear Information System (INIS)

Purpose: To enable optimul and automatic control of the water level in a reactor even when a feedwater control system is operated in a manual mode, such as, at the start, stop and the recovery operation after a scram of the reactor. Constitution: A water level control device for a nuclear reactor is composed of a computer and an analog memory, plant signals from a reactor water level detector, a reactor pressure detector, a feedwater pump discharge pressure detector and a drain water flow rate detector are collected, and the openings of the feedwater control valve and the drain control valve are calculated. Further, the openings of the feedwater control valve and the drain control valve are controlled based on the calculated result, and the water level in the reactor is properly maintained. At this time a communication valve to a condenser remains opened. (Sekiya, K.)

127

Small angle x-ray scattering study of fluctuations in 1-propanol-water and 2-propanol-water systems  

International Nuclear Information System (INIS)

Small-angle x-ray scattering (SAXS) measurements have been carried out on the 1-propanol (NPA)-water system and on the 2-propanol (IPA)-water system at 20 degree C. In the NPA-water system, the zero angle intensity, the concentration fluctuation, the Kirkwood-Buff parameters, and Debye's correlation lengths have been determined at various concentrations. In the IPA-water system, the zero angle intensity and Debye's correlation lengths have also been determined. In both the NPA-water and IPA-water systems, all obtained parameters have maxima at about 0.2 of the mole fraction of alcohol. In terms of these parameters, the mixing state of the NPA-water and IPA-water systems is discussed and compared with that of the TBA-water system

128

Stratigraphic analysis of lake level fluctuations in Lake Ohrid: an integration of high resolution hydro-acoustic data and sediment cores  

Science.gov (United States)

Ancient Lake Ohrid is a steep-sided, oligotrophic, karst lake that was tectonically formed most likely within the Pliocene and often referred to as a hotspot of endemic biodiversity. This study aims on tracing significant lake level fluctuations at Lake Ohrid using high-resolution acoustic data in combination with lithological, geochemical, and chronological information from two sediment cores recovered from sub-aquatic terrace levels at ca. 32 and 60 m water depth. According to our data, significant lake level fluctuations with prominent lowstands of ca. 60 and 35 m below the present water level occurred during Marine Isotope Stage (MIS) 6 and MIS 5, respectively. The effect of these lowstands on biodiversity in most coastal parts of the lake is negligible, due to only small changes in lake surface area, coastline, and habitat. In contrast, biodiversity in shallower areas was more severely affected due to disconnection of today sub-lacustrine springs from the main water body. Multichannel seismic data from deeper parts of the lake clearly image several clinoform structures stacked on top of each other. These stacked clinoforms indicate significantly lower lake levels prior to MIS 6 and a stepwise rise of water level with intermittent stillstands since its existence as water-filled body, which might have caused enhanced expansion of endemic species within Lake Ohrid.

Lindhorst, K.; Vogel, H.; Krastel, S.; Wagner, B.; Hilgers, A.; Zander, A.; Schwenk, T.; Wessels, M.; Daut, G.

2010-11-01

129

Stratigraphic analysis of lake level fluctuations in Lake Ohrid: an integration of high resolution hydro-acoustic data and sediment cores  

Directory of Open Access Journals (Sweden)

Full Text Available Ancient Lake Ohrid is a steep-sided, oligotrophic, karst lake that was tectonically formed most likely within the Pliocene and often referred to as a hotspot of endemic biodiversity. This study aims on tracing significant lake level fluctuations at Lake Ohrid using high-resolution acoustic data in combination with lithological, geochemical, and chronological information from two sediment cores recovered from sub-aquatic terrace levels at ca. 32 and 60 m water depth. According to our data, significant lake level fluctuations with prominent lowstands of ca. 60 and 35 m below the present water level occurred during Marine Isotope Stage (MIS 6 and MIS 5, respectively. The effect of these lowstands on biodiversity in most coastal parts of the lake is negligible, due to only small changes in lake surface area, coastline, and habitat. In contrast, biodiversity in shallower areas was more severely affected due to disconnection of today sub-lacustrine springs from the main water body. Multichannel seismic data from deeper parts of the lake clearly image several clinoform structures stacked on top of each other. These stacked clinoforms indicate significantly lower lake levels prior to MIS 6 and a stepwise rise of water level with intermittent stillstands since its existence as water-filled body, which might have caused enhanced expansion of endemic species within Lake Ohrid.

K. Lindhorst

2010-11-01

130

Pressurized water reactor level instrumentation  

International Nuclear Information System (INIS)

The need for design modifications on both BWRs and PWRs to obtain correct reactor-coolant level indication during abnormal conditions has been receiving greater emphasis since the events at TMI 2. This paper discusses some of the engineering and installation experiences for the plants where Fluor Engineers was involved as the Architect/Engineer (A/E). Described are two units using the standard Westinghouse design of three differential-pressure transmitters per train, as well as a third plant which utilized a design in which only two differential-pressure transmitters per train were used in conjunction with a microprocessor-based monitoring system. Cost savings were achieved by using a unique penetration design and by routing the instrument sense lines in unistrut, using standard cable tray support details. The reactor head attachment was also a unique and cost-effective design which had been analyzed using finite element techniques. Some valuable lessons learned with using cryofit fittings for the instrument sense lines are discussed

131

Time-Reversal Symmetry and Universal Conductance Fluctuations in a Driven Two-Level System  

CERN Document Server

In the presence of time-reversal symmetry, quantum interference gives strong corrections to the electric conductivity of disordered systems. The self-interference of an electron wavefunction traveling time-reversed paths leads to effects such as weak localization and universal conductance fluctuations. Here, we investigate the effects of broken time-reversal symmetry in a driven artificial two-level system. Using a superconducting flux qubit, we implement scattering events as multiple Landau-Zener transitions by driving the qubit periodically back and forth through an avoided crossing. Interference between different qubit trajectories give rise to a speckle pattern in the qubit transition rate, similar to the interference patterns created when coherent light is scattered off a disordered potential. Since the scattering events are imposed by the driving protocol, we can control the time-reversal symmetry of the system by making the drive waveform symmetric or asymmetric in time. We find that the fluctuations o...

Gustavsson, Simon; Oliver, William D

2012-01-01

132

Dynamics of phreatophyte root growth relative to a seasonally fluctuating water table in a Mediterranean-type environment.  

Science.gov (United States)

While seasonal redistribution of fine root biomass in response to fluctuations in groundwater level is often inferred in phreatophytic plants, few studies have observed the in situ growth dynamics of deep roots relative to those near the surface. We investigated the root growth dynamics of two Banksia species accessing a seasonally dynamic water table and hypothesized that root growth phenology varied with depth, i.e. root growth closest to the water table would be influenced by water table dynamics rather than surface micro-climate. Root in-growth bags were used to observe the dynamics of root growth at different soil depths and above-ground growth was also assessed to identify whole-plant growth phenology. Root growth at shallow depths was found to be in synchrony with above-ground growth phenophases, following increases in ambient temperature and soil water content. In contrast, root growth at depth was either constant or suppressed by saturation. Root growth above the water table and within the capillary fringe occurred in all seasons, corresponding with consistent water availability and aerobic conditions. However, at the water table, a seasonal cycle of root elongation with drawdown in summer followed by trimming in response to water table rise and saturation in winter, was observed. The ability to grow roots year-round at the capillary fringe and redistribute fine root biomass in response to groundwater drawdown is considered critical in allowing phreatophytes, in seasonally water-limited environments, to maintain access to groundwater throughout the year. PMID:22692384

Canham, Caroline A; Froend, Raymond H; Stock, William D; Davies, Muriel

2012-12-01

133

Changes in water biostability levels in water treatment trials.  

Science.gov (United States)

This article presents the results of studies of changes in water biostability levels in water treatment systems. In order to evaluate the potential of microorganism regrowth, both the organic and non-organic nutrient substrate content was taken into account. Pre-treatment in the analyzed water treatment plants ensured high phosphate ion removal effectiveness but a significantly worse effectiveness in removing biodegradable dissolved organic carbon (BDOC). Lowering nutrient substrate content during the main treatment stage was only possible in water treatment systems that incorporated biological processes. Conversely, final water treatment processes only influenced BDOC content in the treated water. Irrespective of the water type and unit treatment process, the limiting factors for microorganism regrowth in the distribution system were the phosphate ion content and BDOC content. However, none of the analyzed treatment systems ensured a reduction in non-organic nitrogen content that would ensure biological stability of the water. PMID:25746645

Wolska, Ma?gorzata

2015-01-01

134

Water level indicator for nuclear reactor vessel  

International Nuclear Information System (INIS)

A water level indicator for a pressure vessel is provided which employs a plurality of vertically spaced cantilevered mounted spring members. The free end of each spring member is connected to a depending float member. The float member has sufficient mass and density to depress its spring member when the float member is in a gaseous medium. The float member has sufficient buoyancy to elevate its spring member when the float member is in a water medium. One or more strain gauges is secured to each spring member to indicate the instantaneous position of the spring member and thereby provide an indication of the instantaneous water level

135

Controlling the response of a pressurized water reactor to rapid fluctuations in load  

Energy Technology Data Exchange (ETDEWEB)

Apparatus for controlling the response to a load signal of a pressurized water reactor having controlled process variables is described. It consists of: a control system for effecting control actions to regulate a selected process variable to a value called for by a setpoint reference signal; and means responsive only to rapid fluctuations in the load signal above a predetermined frequency for adjusting the value of the setpoint reference signal by an amount which substantially matches the variation in the value of the selected process variable expected as a result of the rapid fluctuations in the load signal without control action, and taking into account any time delay in the affect of the rapid fluctuations on the selected process variable, whereby control actions effected by the control system are substantially reduced.

Storrick, G.D.

1987-11-17

136

Controlling the response of a pressurized water reactor to rapid fluctuations in load  

International Nuclear Information System (INIS)

Apparatus for controlling the response to a load signal of a pressurized water reactor having controlled process variables is described. It consists of: a control system for effecting control actions to regulate a selected process variable to a value called for by a setpoint reference signal; and means responsive only to rapid fluctuations in the load signal above a predetermined frequency for adjusting the value of the setpoint reference signal by an amount which substantially matches the variation in the value of the selected process variable expected as a result of the rapid fluctuations in the load signal without control action, and taking into account any time delay in the affect of the rapid fluctuations on the selected process variable, whereby control actions effected by the control system are substantially reduced

137

The effect of interaural-level-difference fluctuations on the externalization of sound  

DEFF Research Database (Denmark)

Real-world sound sources are usually perceived as externalized and thus properly localized in both direction and distance. This is largely due to (1) the acoustic filtering by the head, torso, and pinna, resulting in modifications of the signal spectrum and thereby a frequency-dependent shaping of interaural cues and (2) interaural cues provided by the reverberation inside an enclosed space. This study first investigated the effect of room reverberation on the spectro-temporal behavior of interaural level differences (ILDs) by analyzing dummy-head recordings of speech played at different distances in a standard listening room. Next, the effect of ILD fluctuations on the degree of externalization was investigated in a psychoacoustic experiment performed in the same listening room. Individual binaural impulse responses were used to simulate a distant sound source delivered via headphones. The ILDs were altered using a gammatone filterbank for analysis and resynthesis, where the envelopes of the left and right-ear signals were modified such that the naturally occurring fluctuations of the ILDs were restricted. This manipulation reduced the perceived degree of externalization. This was consistent with the analysis of short-term ILDs at different distances showing that a decreased distance to the sound source also reduced the ILD fluctuations. © 2013 Acoustical Society of America.

Catic, Jasmina; Santurette, Sébastien

2013-01-01

138

Fluctuations in Species-Level Protein Expression Occur during Element and Nutrient Cycling in the Subsurface  

Energy Technology Data Exchange (ETDEWEB)

While microbial activities in environmental systems play a key role in the utilization and cycling of essential elements and compounds, microbial activity and growth frequently fluctuates in response to environmental stimuli and perturbations. To investigate these fluctuations within a saturated aquifer system, we monitored a carbon-stimulated in situ Geobacter population while iron reduction was occurring, using 16S rRNA abundances and high-resolution tandem mass spectrometry proteome measurements. Following carbon amendment, 16S rRNA analysis of temporally separated samples revealed the rapid enrichment of Geobacter-like environmental strains with strong similarity to G. bemidjiensis. Tandem mass spectrometry proteomics measurements suggest high carbon flux through Geobacter respiratory pathways, and the synthesis of anapleurotic four carbon compounds from acetyl-CoA via pyruvate ferredoxin oxidoreductase activity. Across a 40-day period where Fe(III) reduction was occurring, fluctuations in protein expression reflected changes in anabolic versus catabolic reactions, with increased levels of biosynthesis occurring soon after acetate arrival in the aquifer. In addition, localized shifts in nutrient limitation were inferred based on expression of nitrogenase enzymes and phosphate uptake proteins. These temporal data offer the first example of differing microbial protein expression associated with changing geochemical conditions in a subsurface environment.

Wilkins, Michael J.; Wrighton, Kelly C.; Nicora, Carrie D.; Williams, Kenneth H.; McCue, Lee Ann; Handley, Kim M.; Miller, C. S.; Giloteaux, L.; Montgomery, A. P.; Lovley, Derek R.; Banfield, Jillian F.; Long, Philip E.; Lipton, Mary S.

2013-03-05

139

Discrete-storm water-table fluctuation method to estimate episodic recharge.  

Science.gov (United States)

We have developed a method to identify and quantify recharge episodes, along with their associated infiltration-related inputs, by a consistent, systematic procedure. Our algorithm partitions a time series of water levels into discrete recharge episodes and intervals of no episodic recharge. It correlates each recharge episode with a specific interval of rainfall, so storm characteristics such as intensity and duration can be associated with the amount of recharge that results. To be useful in humid climates, the algorithm evaluates the separability of events, so that those whose recharge cannot be associated with a single storm can be appropriately lumped together. Elements of this method that are subject to subjectivity in the application of hydrologic judgment are values of lag time, fluctuation tolerance, and master recession parameters. Because these are determined once for a given site, they do not contribute subjective influences affecting episode-to-episode comparisons. By centralizing the elements requiring scientific judgment, our method facilitates such comparisons by keeping the most subjective elements openly apparent, making it easy to maintain consistency. If applied to a period of data long enough to include recharge episodes with broadly diverse characteristics, the method has value for predicting how climatic alterations in the distribution of storm intensities and seasonal duration may affect recharge. PMID:24588378

Nimmo, John R; Horowitz, Charles; Mitchell, Lara

2015-03-01

140

Stratigraphic analysis of lake level fluctuations in Lake Ohrid: an integration of high resolution hydro-acoustic data and sediment cores  

Directory of Open Access Journals (Sweden)

Full Text Available Ancient Lake Ohrid is a steep sided, oligotrophic, karst lake of likely Pliocene age and often referred to as a hotspot of endemic biodiversity. This study aims on tracing significant lake level fluctuations at Lake Ohrid using high-resolution acoustic data in combination with lithological, geochemical, and chronological information from two sediment cores recovered from sub-aquatic terrace levels at ca. 32 and 55 m. According to our data, significant lake level fluctuations with prominent lowstands of ca. 60 and 35 m below the present water level occurred during MIS 6 and MIS 5, respectively. The effect of these lowstands on biodiversity in most coastal parts of the lake is negligible, due to only small changes in lake surface area, coastline, and habitat. In contrast, biodiversity in shallower areas was more severely affected due to disconnection of today sub-lacustrine springs from the main water body. Multichannel seismic data from deeper parts of the lake clearly imaged several clinoform structures stacked on top of each other. These stacked clinoforms indicate significantly lower lake levels prior to MIS 6 and a stepwise rise of water level with intermittent stillstands since its existence as water filled body, which might have caused enhanced expansion of endemic species within Lake Ohrid.

K. Lindhorst

2010-05-01

141

A coupled neutronics/thermal–hydraulics tool for calculating fluctuations in Pressurized Water Reactors  

International Nuclear Information System (INIS)

Highlights: ? Numerical fluctuation calculations for a commercial PWR. ? Fluctuations in neutron flux, fuel and moderator temperature and coolant velocity. ? Coupled models for neutronics and thermal–hydraulics. ? Validated against FLUENT and RELAP5/PARCS. - Abstract: This paper describes a tool for estimating fluctuations in neutron flux, fuel temperature, moderator density and flow velocity in Pressurized Water Reactors by coupling a dynamic thermal–hydraulic module and a dynamic neutron kinetic module. The code calculates the static solution first, giving the profile of the static fuel temperature, moderator density, velocity and neutron flux. The fluctuations (called noise in this work) are the differences between the actual time-dependent values and the corresponding mean values. The fluctuations are in general induced by perturbations in the thermal–hydraulic parameters, e.g. moderator temperature or density, at the inlet of the core. There is also a possibility to directly define the perturbations in the macroscopic cross-sections and to supply them to the neutronic part of the model. The model was validated against two separate calculations using two different commercial tools.

142

Geochemical Changes in the Caspian Salt Marshes Due to the Sea Level Fluctuations  

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Full Text Available The Caspian Sea is subject to alternating transgressions and regressions that exert a strong impact on the topography, sediments, vegetation, and soils in coastal zones. The last transgression of the Caspian Sea (1978-1995 caused the development of a marsh-lagoon system along the accumulative seashore of the Central Dagestan. Salt marshes are complex and dynamic systems highly vulnerable to sea level fluctuations; therefore, they may be considered as a regional model of rapid environmental changes. Hazards in coastal zones may critically change the soil geochemistry affecting agricultural potential of large areas. Assessments of risks of the natural hazards in coastal zones are extremely difficult unless the end-to-end understanding of all natural factors. The research in the Caspian region shows the impact of extreme events in the coastal zones. Detailed landscape-geochemical investigations of the Caspian salt marshes were carried out in 1995-1996 (during the final stage of the transgression period and in 2001-2003 (during the period of the sea level stabilization. These coastal areas are influenced by different landscape-geochemical processes, such as sulfidization, gleyzation, ferrugination, humus accumulation, halogenesis, and changes of alkali-acidic conditions. The development of the processes characterizes different stages of the Caspian Sea level fluctuations. This paper presents a discussion on stages and rates of landscape-geochemical processes, formation of geochemical barriers, and trace elements distribution in soils of the salt marshes.

Nicolay S. Kasimov

2012-05-01

143

Attenuation of concentration fluctuations of water vapor and other trace gases in turbulent tube flow  

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Full Text Available Recent studies with closed-path eddy covariance (EC systems have indicated that the attenuation of fluctuations of water vapor concentration is dependent upon ambient relative humidity, presumably due to sorption/desorption of water molecules at the interior surface of the tube. Previous studies of EC-related tube attenuation effects have either not considered this issue at all or have only examined it superficially. Nonetheless, the attenuation of water vapor fluctuations is clearly much greater than might be expected from a passive tracer in turbulent tube flow. This study reexamines the turbulent tube flow issue for both passive and sorbing tracers with the intent of developing a physically-based semi-empirical model that describes the attenuation associated with water vapor fluctuations. Toward this end, we develop a new model of tube flow dynamics (radial profiles of the turbulent diffusivity and tube airstream velocity. We compare our new passive-tracer formulation with previous formulations in a systematic and unified way in order to assess how sensitive the passive-tracer results depend on fundamental modeling assumptions. We extend the passive tracer model to the vapor sorption/desorption case by formulating the model's wall boundary condition in terms of a physically-based semi-empirical model of the sorption/desorption vapor fluxes. Finally we synthesize all modeling and observational results into a single analytical expression that captures the effects of the mean ambient humidity and tube flow (Reynolds number on tube attenuation.

W. J. Massman

2008-05-01

144

Attenuation of concentration fluctuations of water vapor and other trace gases in turbulent tube flow  

DEFF Research Database (Denmark)

Recent studies with closed-path eddy covariance (EC) systems have indicated that the attenuation of fluctuations of water vapor concentration is dependent upon ambient relative humidity, presumably due to sorption/desorption of water molecules at the interior surface of the tube. Previous studies of EC-related tube attenuation effects have either not considered this issue at all or have only examined it superficially. Nonetheless, the attenuation of water vapor fluctuations is clearly much greater than might be expected from a passive tracer in turbulent tube flow. This study reexamines the turbulent tube flow issue for both passive and sorbing tracers with the intent of developing a physically-based semi-empirical model that describes the attenuation associated with water vapor fluctuations. Toward this end, we develop a new model of tube flow dynamics (radial profiles of the turbulent diffusivity and tube airstream velocity). We compare our new passive-tracer formulation with previous formulations in a systematic and unified way in order to assess how sensitive the passive-tracer results depend on fundamental modeling assumptions. We extend the passive tracer model to the vapor sorption/desorption case by formulating the model's wall boundary condition in terms of a physically-based semi-empirical model of the sorption/desorption vapor fluxes. Finally we synthesize all modeling and observational results into a single analytical expression that captures the effects of the mean ambient humidity and tube flow (Reynolds number) on tube attenuation.

Massman, W.J.; Ibrom, Andreas

2008-01-01

145

Attenuation of concentration fluctuations of water vapor and other trace gases in turbulent tube flow  

Directory of Open Access Journals (Sweden)

Full Text Available Recent studies with closed-path eddy covariance (EC systems have indicated that the attenuation of fluctuations of water vapor concentration is dependent upon ambient relative humidity, presumably due to sorption/desorption of water molecules at the interior surface of the tube. Previous studies of EC-related tube attenuation effects have either not considered this issue at all or have only examined it superficially. Nonetheless, the attenuation of water vapor fluctuations is clearly much greater than might be expected from a passive tracer in turbulent tube flow. This study reexamines the turbulent tube flow issue for both passive and sorbing tracers with the intent of developing a physically-based semi-empirical model that describes the attenuation associated with water vapor fluctuations. Toward this end, we develop a new model of tube flow dynamics (radial profiles of the turbulent diffusivity and tube airstream velocity. We compare our new passive-tracer formulation with previous formulations in a systematic and unified way in order to assess how sensitive the passive-tracer results depend on fundamental modeling assumptions. We extend the passive tracer model to the vapor sorption/desorption case by formulating the model's wall boundary condition in terms of a physically-based semi-empirical model of the sorption/desorption vapor fluxes. Finally we synthesize all modeling and observational results into a single analytical expression that captures the effects of the mean ambient humidity and tube flow (Reynolds number on tube attenuation.

W. J. Massman

2008-10-01

146

Radon levels in riyadh ground water  

International Nuclear Information System (INIS)

Full text: A national ground water surveillance program was started for investigation of natural radioactivity levels. This paper presents 222Rn radioactivity concentration levels in well waters located only in Riyadh area of Saudi Arabia. The 222Rn radioactivity levels were measured in water samples of 146 water wells. These were collected from six locations in Riyadh Area. The analyses were performed by ultra low level liquid scintillation spectrometer equipped with an alpha-beta discrimination device. Efficiency and background calibrations were performed with a 226Ra aqueous standard homogeneously mixed with the cocktail and used after certain period to assure radon equilibrium. Most of these wells are deep wells with about 1000 meter depth. The range of 222Rn activities measured in these deep wells ranged from 0.34±0.04 to 4.63±0.38 BqL-1 with an average of 1.82±0.19 BqL-1, while the activities in shallow wells (?300 meters) ranged from 1.27±0.14 to 6.49±0.45 BqL-1 with an average value of 3.32±0.31BqL-1. The values of 222Rn concentrations were found to be dependant on the water sources. The radioactivity levels of 222Rn in the groundwater are in compliance with the national limits of 300 BqL-1. (author)

147

Characterization of the temperature fluctuations generated in a thermal mixing tee (sodium versus water behavior)  

International Nuclear Information System (INIS)

The temperature fluctuations occurring in 1800 inlet-let angle pipe tee thermal mixers with and without inlet reducer pipes are characterized in both amplitude and frequency. Sodium and water data from different sized tees have allowed delineation of the size and fluid medium modeling laws required for the extrapolation of reduced-scale water model temperature fluctuation data to prototype LMFBR sodium mixers. The phenomena of flow corner cutoff and thermal buoyancy at a tee juncture have also been studied and their effects on mixer performance delineated. The information presented is vital both to the design of thermal-fatigue-free mixers and to the understanding of thermal mixing in complex flows; much of it has not been peviously available

148

Effect of water-table fluctuation on dissolution and biodegradation of a multi-component, light nonaqueous-phase liquid.  

Science.gov (United States)

Light nonaqueous-phase liquids (LNAPLs) such as gasoline and diesel fuel are among the most common causes of soil and groundwater contamination. Dissolution and subsequent advective transport of LNAPL components can negatively impact water supplies, while biodegradation is thought to be an important sink for this class of contaminants. We present a laboratory investigation of the effect of a water-table fluctuation on dissolution and biodegradation of a multi-component LNAPL (85% hexadecane, 5% toluene, 5% ethylbenzene, and 5% 2-methylnapthalene on a molar basis) in a pair of similar model aquifers (80 cm x 50 cm x 3 cm), one of which was subjected to a water-table fluctuation. Water-table fluctuation resulted in LNAPL and air entrapment below the water table, an increase in the vertical extent of the LNAPL source zone (by factor 6.7), and an increase in the volume of water passing through the source zone (by factor ~18). Effluent concentrations of dissolved LNAPL components were substantially higher and those of dissolved nitrate lower in the model aquifer where a fluctuation had been induced. Thus, water-table fluctuation led to enhanced biodegradation activity (28.3 mmol of nitrate consumed compared to 16.3 mmol in the model without fluctuation) as well as enhanced dissolution of LNAPL components. Despite the increased biodegradation, fluctuation led to increased elution of dissolved LNAPL components from the system (by factors 10-20). Hence, water-table fluctuations in LNAPL-contaminated aquifers might be expected to result in increased exposure of downgradient receptors to LNAPL components. Accordingly, water-table fluctuations in contaminated aquifers are probably undesirable unless the LNAPL is of minimal solubility or the dissolved-phase plume is not expected to reach a receptor due to distance or the presence of some form of containment. PMID:17698242

Dobson, Richard; Schroth, Martin H; Zeyer, Josef

2007-12-01

149

Drought impact on water use efficiency and intra-annual density fluctuations in Erica arborea on Elba (Italy).  

Science.gov (United States)

Erica arborea (L) is a widespread Mediterranean species, able to cope with water stress and colonize semiarid environments. The eco-physiological plasticity of this species was evaluated by studying plants growing at two sites with different soil moistures on the island of Elba (Italy), through dendrochronological, wood-anatomical analyses and stable isotopes measurements. Intra-annual density fluctuations (IADFs) were abundant in tree rings, and were identified as the key parameter to understand site-specific plant responses to water stress. Our findings showed that the formation of IADFs is mainly related to the high temperature, precipitation patterns and probably to soil water availability, which differs at the selected study sites. The recorded increase in the (13) C-derived intrinsic water use efficiency at the IADFs level was linked to reduced water loss rather than to increasing C assimilation. The variation in vessel size and the different absolute values of ?(18) O among trees growing at the two study sites underlined possible differences in stomatal control of water loss and possible differences in sources of water uptake. This approach not only helped monitor seasonal environmental differences through tree-ring width, but also added valuable information on E.?arborea responses to drought and their ecological implications for Mediterranean vegetation dynamics. PMID:23848555

Battipaglia, Giovanna; DE Micco, Veronica; Brand, Willi A; Saurer, Matthias; Aronne, Giovanna; Linke, Petra; Cherubini, Paolo

2014-02-01

150

Arrival-time fluctuations of coherent reflections from surface gravity water waves.  

Science.gov (United States)

Arrival time fluctuations of coherent reflections from surface gravity waves are examined. A two-dimensional ray model with an evolving rough sea surface is used to explain the mechanism and formation of the deterministic striation patterns due to the surface reflection. Arrival time predictions from the ray model match qualitatively well with the measurements from bidirectional acoustic transmissions in a water depth of 100?m. PMID:24815293

Badiey, Mohsen; Eickmeier, Justin; Song, Aijun

2014-05-01

151

Water Level Detection Using Synthetic Aperture Radar Imagery  

International Nuclear Information System (INIS)

Reservoir water levels are of interest for international safeguards and domestic monitoring because they can be used as indicators of processing activity, uranium mine tailings protection status, or power generation for clandestine operation. Monitoring of water levels using satellite technology, especially civilian synthetic aperture radar (SAR) for remote or restricted-access sites worldwide has the potential to be a valuable tool for national/international safeguards as well as environmental monitoring applications. Unlike optical sensors, SAR is capable of reliable repeat monitoring regardless of cloud cover or solar illumination, i.e. it can image the target through clouds and darkness. Because of this ability, quick turn around for a SAR image is almost always guaranteed. SAR is very sensitive to the land/water interface and can be used to extract detailed elevation models. SAR is also sensitive to metallic structures or objects and can thus be useful in detection of heavy equipment or undeclared construction at decommissioned facilities. Although spaceborne SAR cannot match the resolution of optical satellites, future SAR satellites will offer much better resolution (e.g., approximately 3 metres for RADARSAT-2). Furthermore, future SAR satellites will offer different polarization and frequency channels to provide terrain and vegetation classification. The objective is to investigate the use of SAR for water level detection using Canada's RADARSAT-1 imagery. Thrion using Canada's RADARSAT-1 imagery. Three Canadian sites were chosen for our study: Niagara Area Hydro Reservoir; Quirke Lake uranium tailings management facility (TMF); and JEB Pit TMF. Initial results, using RADARSAT-1 data acquired over a three year period, show dramatic changes in both the total water surface area and markers (natural or man-made) becoming visible as the water level decreases. These very promising results indicated that SAR imagery can be used as an excellent tool for mapping remote location (which is useful for inspection planning), object detection (verification of declared activities, or detection of undeclared activities), and detection of water level fluctuation (which may be linked to a clandestine power generation during a period where optical sensors are not effective, e.g. at night or during adverse weather conditions). Additional analysis of RADARSAT-1 data, supportable by ground truth information and IKONOS imagery, is being carried out and further results are expected to be available soon. Large steep walled or terraced reservoirs, as in the case of JEB Pit TMF would require a different analysis technique. Scoping work indicated that it would be possible to deduce the water level by measuring the wall height using 'radar shadow', in a manner similar to the exploitation of shadows in optical images

152

On the Hofmeister effect: fluctuations at the protein-water interface and the surface tension.  

Science.gov (United States)

We performed molecular dynamics simulations on the tryptophane-cage miniprotein using a nonpolarizable force field, in order to model the effect of concentrated water solutions of neutral salts on protein conformation, which is a manifestation of Hofmeister effects. From the equilibrium values and the fluctuations of the solvent accessible surface area of the miniprotein, the salt-induced changes of the mean value of protein-water interfacial tension were determined. At 300 K, the chaotropic ClO4(-) and NO3(-) decreased the interfacial tension according to their position in the Hofmeister series (by approximately 5 and 2.7 mN/m, respectively), while the kosmotropic F(-) increased it (by 1 mN/m). These values were compared to those obtained from the Gibbs equation using the excess surface adsorption calculated from the probability distribution of the water molecules and ions around the miniprotein, and the two sets were found to be very close to each other. Our results present a direct evidence for the central role of interfacial tension and fluctuations at the protein-water interface in Hofmeister phenomena, and provide a computational method for the determination of the protein-water interfacial tension, establishing a link between the phenomenological and microscopic description of protein-water interfaces. PMID:24977301

Bogár, Ferenc; Bartha, Ferenc; Násztor, Zoltán; Fábián, László; Leitgeb, Balázs; Dér, András

2014-07-24

153

Terahertz target illumination fluctuation estimates derived from field measurements of atmospheric water vapor  

Science.gov (United States)

Many terahertz imaging systems under development will be employed in outdoor environments, where spatial and temporal fluctuations of atmospheric absorbing species can affect image quality. Absorption across most of the terahertz band is dominated by water vapor. Active systems that illuminate targets with scanned ("flying spot") or floodlight terahertz sources will experience some spatial and temporal noise modulation of target plane irradiance due to path-integrated inhomogeneities in the turbulent water vapor density field. We have analyzed data collected during field measurement campaigns conducted at the White Sands Missile Range during the spring and summer of 2007 for spectral characteristics and diurnal variations of water vapor fluctuations under dry to moderately humid synoptic conditions. The results of these analyses were then used to model the statistics of irradiance fluctuations that might be observed in the target plane of a THz imager under varying propagation conditions. The measurements acquired can also be compared with a statistical model of path-integrated absorptance considering either the evolution of the absorption with time or the effects of decorrelation in absorber for two angularly separated lines-of-sight.

O'Brien, Sean G.; Tofsted, David H.

2008-04-01

154

Effects of a long term water level reduction on the ecology and water quality in an eastern Mediterranean lake  

Directory of Open Access Journals (Sweden)

Full Text Available Water level fluctuations play a significant role in the lake nutrient dynamics, and consequently may have a strong influence on the biological communities and productivity. In this article we investigated the effects of a long term water level reduction on key chemistry parameters and major biological communities in an eastern Mediterranean lake. Our approach is based on temporal data regarding water quality, fish, zooplankton and aquatic vegetation that are representative of different water level periods. The results revealed significant correlations between water level, conductivity and chloride concentration suggesting a clear effect of the water level reduction on the water quality. Among the key findings of this study is the significant increase of zoobenthivorous fish (roach and carp from 1973 to 1999 that correlates with the water level reduction. A decline of charophytes is also noted whereas the reed beds appear to have expanded at the shallower parts of the lake. The zooplankton composition of the lake is mostly dominated by nauplii, rotifer and small-sized crustaceans indicating a possible effect of fish predation. Overall, this article has ascertained an alarming shift of water quality and composition of biological communities that can be attributed to the combined effects of eutrophication and the extreme water level decrease.

Stefanidis K.

2013-09-01

155

Multifractal detrended fluctuation analysis in examining scaling properties of the spatial patterns of soil water storage  

Directory of Open Access Journals (Sweden)

Full Text Available Knowledge about the scaling properties of soil water storage is crucial in transferring locally measured fluctuations to larger scales and vice-versa. Studies based on remotely sensed data have shown that the variability in surface soil water has clear scaling properties (i.e., statistically self similar over a wider range of spatial scales. However, the scaling property of soil water storage to a certain depth at a field scale is not well understood. The major challenges in scaling analysis for soil water are the presence of localized trends and nonstationarities in the spatial series. The objective of this study was to characterize scaling properties of soil water storage variability through multifractal detrended fluctuation analysis (MFDFA. A field experiment was conducted in a sub-humid climate at Alvena, Saskatchewan, Canada. A north-south transect of 624-m long was established on a rolling landscape. Soil water storage was monitored weekly between 2002 and 2005 at 104 locations along the transect. The spatial scaling property of the surface 0 to 40 cm depth was characterized using the MFDFA technique for six of the soil water content series (all gravimetrically determined representing soil water storage after snowmelt, rainfall, and evapotranspiration. For the studied transect, scaling properties of soil water storage are different between drier periods and wet periods. It also appears that local controls such as site topography and texture (that dominantly control the pattern during wet states results in multiscaling property. The nonlocal controls such as evapotranspiration results in the reduction of the degree of multiscaling and improvement in the simple scaling. Therefore, the scaling property of soil water storage is a function of both soil moisture status and the spatial extent considered.

A. Biswas

2012-03-01

156

Sedimentary constraints on late Quaternary lake-level fluctuations at Bear Lake, Utah and Idaho  

Science.gov (United States)

A variety of sedimentological evidence was used to construct the lake-level history for Bear Lake, Utah and Idaho, for the past ???25,000 years. Shorelines provide evidence of precise lake levels, but they are infrequently preserved and are poorly dated. For cored sediment similar to that in the modern lake, grain-size distributions provide estimates of past lake depths. Sedimentary textures provide a highly sensitive, continuous record of lake-level changes, but the modern distribution of fabrics is poorly constrained, and many ancient features have no modern analog. Combining the three types of data yields a more robust lake-level history than can be obtained from any one type alone. When smooth age-depth models are used, lake-level curves from multiple cores contain inconsistent intervals (i.e., one record indicates a rising lake level while another record indicates a falling lake level). These discrepancies were removed and the multiple records were combined into a single lake-level curve by developing age-depth relations that contain changes in deposition rate (i.e., gaps) where indicated by sedimentological evidence. The resultant curve shows that, prior to 18 ka, lake level was stable near the modern level, probably because the lake was overflowing. Between ca. 17.5 and 15.5 ka, lake level was ???40 m below the modern level, then fluctuated rapidly throughout the post-glacial interval. Following a brief rise centered ca. 15 ka ( = Raspberry Square phase), lake level lowered again to 15-20 m below modern from ca. 14.8-11.8 ka. This regression culminated in a lowstand to 40 m below modern ca. 12.5 ka, before a rapid rise to levels above modern ca. 11.5 ka. Lake level was typically lower than present throughout the Holocene, with pronounced lowstands 15-20 m below the modern level ca. 10-9, 7.0, 6.5-4.5, 3.5, 3.0-2.5, 2.0, and 1.5 ka. High lake levels near or above the modern lake occurred ca. 8.5-8.0, 7.0-6.5, 4.5-3.5, 2.5, and 0.7 ka. This lake-level history is more similar to records from Pyramid Lake, Nevada, and Owens Lake, California, than to those from Lake Bonneville, Utah. Copyright ?? 2009 The Geological Society of America.

Smoot, J.P.; Rosenbaum, J.G.

2009-01-01

157

Investment choice and perceived mating intentions regulated by external resource cues and internal fluctuation in blood glucose levels  

Science.gov (United States)

We examined resource allocation priorities in the framework of an updated Maslow hierarchy of fundamental human needs. In Experiment 1, the participants in the food abundance priming condition viewing photos of high-calorie food allocated more money to savings than to spending. However, the participants preferred spending to savings under the condition of mating availability priming with romantic photographs. In Experiment 2, before and after drinking either water or a sugary beverage, fasting participants rated photos of a conversation between a man and a woman. Water drinking lowered the rating scores of mating intentions as well as blood glucose (BG) levels. The sugary drink buffered this decline in sexual perceptivity. Overall, the change in BG levels was positively associated with changes in the ratings of mating intentions but was not associated with other likelihood ratings. These results suggest that both external cues of food and mating resources and internal BG fluctuation regulate the cognitive priority of physiological needs vs. mate acquisition and retention. PMID:25610412

Rao, Li-Lin; Wang, Xiao-Tian; Li, Shu

2015-01-01

158

Orbital forced sea level fluctuations during the Middle Eocene (ODP site 1172, East Tasman Plateau)  

Science.gov (United States)

Ocean Drilling Program leg 189 was undertaken to test and refine the hypothesis (by Kennett et al., 1975), that the reconfiguration of continents around Antarctica (e.g.: the opening of the Tasmanian Gateway and Drake passage) led to the onset of the Antarctic Circumpolar Current that, in turn, would cause thermal isolation and hence cooling of Antarctica. This would possibly even cause global cooling, as suggested by the 33.3 Ma Oi1 event. The cores of leg 189, site 1172 on the eastern side of the Tasmanian Gateway provided a nearly complete succession of Eocene and Oligocene sediments. Cyclostratigraphic analysis based on XRF derived Ca and Fe records indicates distinct Milankovitch cyclicity between 40 and 36 Ma. (Röhl et al, in press). In the core-section representing magnetochron 18n-1n, the Ca record shows precession cycles in combination with obliquity, suggested to reflect sea level fluctuations (Röhl et al, in press). New datasets include microfossil data (organic-walled dinoflagellate cysts, pollen/spores and diatoms), loss-on-ignition measurements, magnetic data (environmental magnetics - ARM). Here, we aim to further investigate the proposed relationship between astronomical forcing and sea-level fluctuations. Additionally, we aim to obtain insight in the palaeoecology of the distinct endemic circum-Antarctic late Middle to Late Eocene dinoflagellate cyst assemblages. Results corroborate the concept that the cyclicity recorded by Ca and Fe measurements is the result of sea-level fluctuations. This implies that during late Middle Eocene times, astronomical forcing has modulated sea level - most likely through Antarctic ice buildup and meltdown. In turn, this would indicate the presence of significant, though probably modest, ice masses already ~40 Ma ago, well before the onset of the Antarctic Circumpolar Current. Kennett, J. P., R. E. Houtz, et al. (1975). Development of the circum-Antarctic current. Science 186: 144-147. Röhl, U.; H. Brinkhuis, C.E. Stickley, M. Fuller, S.A. Schellenberg, G. Wefer, G. Williams, Cyclostratigraphy of Middle and Late Eocene sediments from the East Tasman Plateau (site 1172), in press.

Warnaar, J.; Stickley, C.; Jovane, L.; Roehl, U.; Brinkhuis, H.; Visscher, H.

2004-12-01

159

Hydro static water level systems at Fermilab  

Energy Technology Data Exchange (ETDEWEB)

Several Hydrostatic Water Leveling systems (HLS) are in use at Fermilab. Three systems are used to monitor quadrupoles in the Tevatron and two systems are used to monitor ground motion for potential sites for the International Linear Collider (ILC). All systems use capacitive sensors to determine the water level of water in a pool. These pools are connected with tubing so that relative vertical shifts between sensors can be determined. There are low beta quadrupoles at the B0 and D0 interaction regions of Tevatron accelerator. These quadrupoles use BINP designed and built sensors and have a resolution of 1 micron. All regular lattice superconducting quadrupoles (a total of 204) in the Tevatron use a Fermilab designed system and have a resolution of 6 microns. Data on quadrupole motion due to quenches, changes in temperature will be presented. In addition data for ground motion for ILC studies caused by natural and cultural factors will be presented.

Volk, J.T.; Guerra, J.A.; Hansen, S.U.; Kiper, T.E.; Jostlein, H.; Shiltsev, V.; Chupyra, A.; Kondaurov, M.; Singatulin, S.

2006-09-01

160

Hydro static water level systems at Fermilab  

International Nuclear Information System (INIS)

Several Hydrostatic Water Leveling systems (HLS) are in use at Fermilab. Three systems are used to monitor quadrupoles in the Tevatron and two systems are used to monitor ground motion for potential sites for the International Linear Collider (ILC). All systems use capacitive sensors to determine the water level of water in a pool. These pools are connected with tubing so that relative vertical shifts between sensors can be determined. There are low beta quadrupoles at the B0 and D0 interaction regions of Tevatron accelerator. These quadrupoles use BINP designed and built sensors and have a resolution of 1 micron. All regular lattice superconducting quadrupoles (a total of 204) in the Tevatron use a Fermilab designed system and have a resolution of 6 microns. Data on quadrupole motion due to quenches, changes in temperature will be presented. In addition data for ground motion for ILC studies caused by natural and cultural factors will be presented

161

Kinetic parameters and intraindividual fluctuations of ochratoxin A plasma levels in humans  

Energy Technology Data Exchange (ETDEWEB)

The mycotoxin ochratoxin A (OTA) is a rodent carcinogen produced by species of the ubiquitous fungal genera Aspergillus and Penicillium. OTA is found in a variety of food items and as a consequence is also found in human plasma (average concentrations found in this study: 0.1-1 ng OTA/ml plasma). To improve the scientific basis for cancer risk assessment the toxicokinetic profile of OTA was studied in one human volunteer following ingestion of 395 ng {sup 3}H-labeled OTA (3.8 {mu}Ci). A two-compartment open model consisting of a central compartment was found to best describe the in vivo data. This two-compartment model consisted of a fast elimination and distribution phase (T{sub 1/2} about 20 h) followed by a slow elimination phase (renal clearance about 0.11 ml/min.) and a calculated plasma half-life of 35.55 days. This half-life was approximately eight times longer than that determined previously in rats. In addition, the intraindividual fluctuation of OTA plasma levels was investigated in eight individuals over a period of 2 months. The concentrations determined ranged between 0.2 and 0.9 ng OTA/ml plasma. The plasma levels in some individuals remained nearly constant over time, while others varied considerably (e.g. increase of 0.4 ng/ml within 3 days, decrease of 0.3 ng/ml within 5 days) during the observation period. This intraindividual fluctuation in OTA plasma levels, which may represent differences in OTA exposure and/or metabolism, as well as the large difference in plasma half-life in humans compared to rats must be taken into consideration when the results of rat cancer study data are extrapolated to humans for risk assessment purposes. (orig.)

Studer-Rohr, I. [Inst. of Toxicology, Swiss Federal Inst. of Tech. and Univ. of Zurich, Schwerzenbach (Switzerland); Dept. of Food Science, Swiss Federal Inst. of Tech., Zurich (Switzerland); Schlatter, J. [Toxicology Section, Div. of Food Science, Swiss Federal Office of Public Health, Zurich (Switzerland); Dietrich, D.R. [Dept. of Environmental Toxicology, Univ. of Konstanz, Konstanz (Germany); Inst. of Toxicology, Swiss Federal Inst. of Tech. and Univ. of Zurich, Schwerzenbach (Switzerland)

2000-11-01

162

Analysis and improvements of module incidental interference faults of water level control system pressurize NPP  

International Nuclear Information System (INIS)

In Daya Bay nuclear power plant, there have been many times that the module used to value the water level outputs a small pulse interference when the pressurizer water level control system is in operation, and the interference exists only in analog storage operation module, which can directly impact the control of the water level of the pressurizer, causing the water level fluctuations and adversely affecting the safe operation of the reactor. This paper analyzes the module incidental interference faults of the water level control system of the NPP pressurizer from the point view of the system control and design of module hardware, and finds out the reasons by the system simulation experiment and power supply circuit test. It is suggested to further improve on the design of hardware loops, add more inductance and capacity to eliminate the interference. (authors)

163

Laser phase fluctuations in a four-level atomic system in N-configuration  

Science.gov (United States)

We discuss here the effect of laser phase fluctuations on coherent spectroscopy of four-level N-system interacting with a trichromatic radiation field of frequencies ? i , ( i = 1-3). The laser phase variables are described by the Wiener-Levy diffusion process to specify the bandwidths ( ? i ) and cross-correlations ( ? ij ) that may exist between pairs of laser fields. A general formalism based on the master equation and theory of multiplicative stochastic processes is developed and used to study three-photon and (2+1)-photon absorptive resonances in model N-system of 40Ca+ ion. It is observed that the resonances are suppressed or broadened by all ? i ,( i = 1-3), while their revival is dependent only on ? 12 and ? 23, and yet the revival is only partial even when the relevant fields are critically correlated. In contrast ? 13 is observed to deteriorate the absorptive resonances. The distinctive features of the steady state and time dependent behavior of the system under three-photon and (2 + 1)-photon resonance conditions and for fluctuating fields are discussed.

Singh, N.; D'Souza, R.; Lawande, Q. V.; Jagatap, B. N.

2013-06-01

164

Quantum fluctuations and isotope effects in ab initio descriptions of water  

International Nuclear Information System (INIS)

Isotope substitution is extensively used to investigate the microscopic behavior of hydrogen bonded systems such as liquid water. The changes in structure and stability of these systems upon isotope substitution arise entirely from the quantum mechanical nature of the nuclei. Here, we provide a fully ab initio determination of the isotope exchange free energy and fractionation ratio of hydrogen and deuterium in water treating exactly nuclear quantum effects and explicitly modeling the quantum nature of the electrons. This allows us to assess how quantum effects in water manifest as isotope effects, and unravel how the interplay between electronic exchange and correlation and nuclear quantum fluctuations determine the structure of the hydrogen bond in water

165

Relative lake level fluctuations and their influence on productivity and resilience in tropical lakes and reservoirs  

OpenAIRE

Lakes and reservoirs are traditionally characterised from static morphological or chemical parameters such as depth and dissolved solids, while the dynamic impact of shifting water supplies has received little attention. There is increasing evidence, however, that the hydrodynamic regime in tropical water bodies plays a significant role in the injection and re-suspension of nutrients, and consequently has a strong influence on the biological communities and productivity. Lake level fluctuatio...

Kolding, J.; Zwieten, P. A. M.

2012-01-01

166

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

Directory of Open Access Journals (Sweden)

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.

L. Duan

2011-04-01

167

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

International Nuclear Information System (INIS)

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

168

Relative sea-level fluctuations since deglaciation in western North America  

Science.gov (United States)

We synthesize the state of knowledge regarding post-glacial sea-level changes on the Pacific coast of North America based on more than 2,000 radiocarbon dates from Oregon to Alaska. Relative sea-level (RSL) history over the late Quaternary is complex owing to regional differences in crustal deformation (neotectonics), changes in global ocean volumes (eustasy) and the depression and rebound of the Earth's crust in response to ice sheets on land (isostasy). The RSL history is further complicated by the diachronous timing of the Last Glacial Maximum (LGM) and subsequent ice retreat across the region. For instance, the LGM ranged in timing from as early as 25 ka (14C years) BP in south-central Alaska, to between 15-14 ka BP at its southernmost extent in southwest BC and northern Washington. During this time, the Cordilleran Ice Sheet depressed the crust over which it formed and, as the ice thinned and retreated, the sea rapidly transgressed isostatically depressed lowland areas. Early-postglacial RSL highstands within the region range from ~25 masl in Cook Inlet, Alaska, to approximately 200 masl at fjord head locations such as Kitimat and in the Lower Mainland of southern BC. As the crust rebounded, RSL dropped. In contrast to the BC mainland, sea levels at the LGM were 150 m lower than present in Haida Gwaii on BC's north coast, due to an isostatic forebulge raising the land. Forebulge collapse led to a rise in relative sea level, up to about 15-18 masl by 9.5 ka BP. Spatial and temporal gaps exist in our understanding of post-glacial sea-level change and landscape evolution along the Pacific coast as data constraining RSL fluctuations around the LGM are limited (e.g. south-central Alaska). Similarly, we lack understanding of post-glacial sea-level fluctuations on BC's central coast. We present an overview of the differences in RSL patterns from Oregon to south-central Alaska and discuss the geophysical foundations for them, as well as present new data filling data gaps on the central BC coast.

Shugar, D. H.; Walker, I. J.; Lian, O. B.; Eamer, J.; Neudorf, C. M.

2013-12-01

169

The roles of shear and cross-correlations on the fluctuation levels in simple stochastic models. Revision  

International Nuclear Information System (INIS)

Highly simplified models of random flows interacting with background microturbulence are analyzed. In the limit of very rapid velocity fluctuations, it is shown rigorously that the fluctuation level of a passively advected scalar is not controlled by the rms shear. In a model with random velocities dependent only on time, the level of cross-correlations between the flows and the background turbulence regulates the saturation level. This effect is illustrated by considering a simple stochastic-oscillator model, both exactly and with analysis and numerical solutions of the direct-interaction approximation. Implications for the understanding of self-consistent turbulence are discussed briefly

170

Contribution of climate-driven change in continental water storage to recent sea-level rise  

OpenAIRE

Using a global model of continental water balance, forced by interannual variations in precipitation and near-surface atmospheric temperature for the period 1981–1998, we estimate the sea-level changes associated with climate-driven changes in storage of water as snowpack, soil water, and ground water; storage in ice sheets and large lakes is not considered. The 1981–1998 trend is estimated to be 0.12 mm/yr, and substantial interannual fluctuations are inferred; for 1993–1998, the trend...

Milly, P. C. D.; Cazenave, A.; Gennero, C.

2003-01-01

171

Trend Estimation of Blood Glucose Level Fluctuations Based on Data Mining  

Directory of Open Access Journals (Sweden)

Full Text Available We have fabricated calorie-calculating software that calculates and records the total calorific food intake by choosing a meal menu selected using a computer mouse. The purpose of this software was to simplify data collection throughout a person's normal life, even if they were inexperienced computer operators. Three portable commercial devices have also been prepared a blood glucose monitor, a metabolic rate monitor and a mobile-computer, and linked into the calorie-calculating software. Time-course changes of the blood glucose level, metabolic rate and food intake were measured using these devices during a 3 month period. Based on the data collected in this study we could predict blood glucose levels of the next morning (FBG by modeling using data mining. Although a large error rate was found for predicting the absolute value, conditions could be found that improved the accuracy of the predicting trends in blood glucose level fluctuations by up to 90 %. However, in order to further improve the accuracy of estimation it was necessary to obtain further details about the patients' life style or to optimise the input variables that were dependent on each patient rather than collecting data over longer periods.

Masaki Yamaguchi

2003-06-01

172

GNSS-Reflectometry based water level monitoring  

Science.gov (United States)

Due to climate changing conditions severe changes in the Mekong delta in Vietnam have been recorded in the last years. The goal of the German Vietnamese WISDOM (Water-related Information system for the Sustainable Development Of the Mekong Delta) project is to build an information system to support and assist the decision makers, planners and authorities for an optimized water and land management. One of WISDOM's tasks is the flood monitoring of the Mekong delta. Earth reflected L-band signals from the Global Navigation Satellite System show a high reflectivity on water and ice surfaces or on wet soil so that GNSS-Reflectometry (GNSS-R) could contribute to monitor the water level in the main streams of the Mekong delta complementary to already existing monitoring networks. In principle, two different GNSS-R methods exist: the code- and the phase-based one. As the latter being more accurate, a new generation of GORS (GNSS Occultation, Reflectometry and Scatterometry) JAVAD DELTA GNSS receiver has been developed with the aim to extract precise phase observations. In a two week lasting measurement campaign, the receiver has been tested and several reflection events at the 150-200 m wide Can Tho river in Vietnam have been recorded. To analyze the geometrical impact on the quantity and quality of the reflection traces two different antennas height were tested. To track separately the direct and the reflected signal, two antennas were used. To derive an average height of the water level, for a 15 min observation interval, a phase model has been developed. Combined with the coherent observations, the minimum slope has been calculated based on the Least- Squares method. As cycle slips and outliers will impair the results, a preprocessing of the data has been performed. A cycle slip detection strategy that allows for automatic detection, identification and correction is proposed. To identify outliers, the data snooping method developed by Baarda 1968 is used. In this context, issues related to the stochastic modeling of GPS observations are addressed and a first model is proposed. First results of water level derivation with precisions below decimeter level are presented. These results could then be used as an approximation for the next computation step: the ambiguities fixing.

Beckheinrich, Jamila; Schön, Steffen; Beyerle, Georg; Apel, Heiko; Semmling, Maximilian; Wickert, Jens

2013-04-01

173

Thermal striping temperature fluctuation analysis using the algebraic stress turbulence model in water and sodium  

International Nuclear Information System (INIS)

A three-dimensional temperature fluctuation analysis was carried out using a general-purpose multidimensional thermohydraulic analysis code for a 1 : 2 scale model water experiment and a 1 : 1 scale model sodium experiment simulating thermal striping phenomena. The code was incorporated with an algebraic stress turbulence model (ASM) and an adaptive control system based on the fuzzy theory to control time step sizes. Calculational results under the test conditions of various flow velocity ratios showed good agreement with the measured intensity distribution and maximum value of the temperature fluctuations. From the analysis, it was concluded that (1) the ASM is applicable to the intensity evaluation of the temperature fluctuations related to the thermal striping phenomena, (2) a combined approach of the ASM and the higher-order accurate schemes such as the quadratic upstream interpolation for convective kinematics (QUICK) and QUICK with the filtering remedy and methodology (FRAM) is recommended to analyze overall turbulent flow and temperature fields in engineering applications, and (3) the adaptive time step size control system is practical in reducing computing efforts. (author)

174

Calculated excitation and ionization yields and fluctuations in irradiated water in the liquid and vapor phases  

International Nuclear Information System (INIS)

Two Monte Carlo computer codes developed independently at ORNL and GSF have been used to compute the slowing down of electrons in water in the liquid and vapor phases. Calculated excitation and ionization yields for the two phases are compared. The distributions in the number of ionizations produced by electrons of various initial energies are presented. Fluctuations in the ionization yields from different shells are expressed by the corresponding Fano factors. The Fano factor for total ionization is about 0.15 for elecrons of energies ? 200 eV in the liquid compared with about 0.25 in the vapor

175

Alluvial deposition and lake-level fluctuations forced by Late Quaternary climate change: the Dead Sea case example  

Science.gov (United States)

Based on geomorphic observations, we discuss lake-level fluctuations, alluvial deposition and river entrenchment in the Dead Sea-Wadi Araba area. The bulk of alluvium in the northern Wadi Araba was probably deposited before the Lisan period of lake transgression that started at about 70 kyears B.P. The lake reached a maximum elevation about 150 m below sea level (b.s.l.), possibly around 15 cal. kyears B.P. as indicated by the highest preserved beach ridges. Cosmogenic exposure dates show that the ridge material consists mainly of remobilized Pleistocene gravel indicating little sediment supply during most of the Lisan period. During this period, a reduced sediment flux fed subaquatic fan deltas along the margin of the Dead Sea. Wetter conditions settled at the end of this period, the water level rose to about 280 m b.s.l. around 15 kyears B.P. and prevailed in the early Holocene (10.5-7 cal. kyears B.P.). Following that humid period, the lake level dropped and two major episodes of fluvial aggradation occurred during periods of relative low lake level. The first aggradational episode took place between about 7.0 and 6.2 cal. kyears B.P. Beach bars indicate a subsequent lake transgression between 6.2 and 4.4 kyears B.P. up to 350 m b.s.l. The second aggradational episode happened between 4.4 and 2.0 cal. kyears B.P., and was also followed by a late transgression up to 375 m b.s.l., dated to 1960-1715 cal. years B.P. The correlation between low lake level and fluvial aggradation is taken to reflect the synchronous change of the fluvial regime and of the lake hydrologic balance, forced by climate changes, rather than a base-level control. We also exclude large tectonic forcing on fan emplacement and river entrenchment. Alluviation appears in this setting as a very irregular process, characterized by long periods of quiescence alternating with periods of fan build-up, reflecting the transient response of the water drainage system to climate change.

Klinger, Y.; Avouac, J. P.; Bourles, D.; Tisnerat, N.

2003-11-01

176

Relationship between fluctuations in glucose levels measured by continuous glucose monitoring and vascular endothelial dysfunction in type 2 diabetes mellitus  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Fluctuations in blood glucose level cause endothelial dysfunction and play a critical role in onset and/or progression of atherosclerosis. We hypothesized that fluctuation in blood glucose levels correlate with vascular endothelial dysfunction and that this relationship can be assessed using common bedside medical devices. Methods Fluctuations in blood glucose levels were measured over 24?hours by continuous glucose monitoring (CGM on admission day 2 in 57 patients with type 2 diabetes mellitus. The reactive hyperemia index (RHI, an index of vascular endothelial function, was measured using peripheral arterial tonometry (EndoPAT on admission day 3. Results The natural logarithmic-scaled RHI (L_RHI correlated with SD (r=?0.504; PPP=0.001 and percentage of time ?200?mg/dl (r=?0.292; P=0.028. In 12 patients with hypoglycemia, L_RHI also correlated with the percentage of time at hypoglycemia (r=?0.589; P=0.044. L_RHI did not correlate with HbA1c or fasting plasma glucose levels. Furthermore, L_RHI did not correlate with LDL cholesterol, HDL cholesterol, and triglyceride levels or with systolic and diastolic blood pressures. Finally, multivariate analysis identified MAGE as the only significant determinant of L_RHI. Conclusions Fluctuations in blood glucose levels play a significant role in vascular endothelial dysfunction in type 2 diabetes. Trial registration UMIN000007581

Torimoto Keiichi

2013-01-01

177

Hunger games: fluctuations in blood glucose levels influence support for social welfare.  

Science.gov (United States)

Social-welfare policies are a modern instantiation of a phenomenon that has pervaded human evolutionary history: resource sharing. Ancestrally, food was a key shared resource in situations of temporary hunger. If evolved human psychology continues to shape how individuals think about current, evolutionarily novel conditions, this invites the prediction that attitudes regarding welfare politics are influenced by short-term fluctuations in hunger. Using blood glucose levels as a physiological indicator of hunger, we tested this prediction in a study in which participants were randomly assigned to conditions in which they consumed soft drinks containing either carbohydrates or an artificial sweetener. Analyses showed that participants with experimentally induced low blood glucose levels expressed stronger support for social welfare. Using an incentivized measure of actual sharing behavior (the dictator game), we further demonstrated that this increased support for social welfare does not translate into genuinely increased sharing motivations. Rather, we suggest that it is "cheap talk" aimed at increasing the sharing efforts of other individuals. PMID:24171932

Aarøe, Lene; Petersen, Michael Bang

2013-12-01

178

Hydrostatic Water Level Systems At Homestake DUSEL  

Science.gov (United States)

Two arrays of Fermilab-style hydrostatic water level sensors have been installed in the former Homestake gold mine in Lead, SD, the site of the new Deep Underground Science and Engineering Laboratory (DUSEL). Sensors were constructed at Fermilab from 8.5 cm diameter PVC pipe (housing) that was sealed on the ends and fit with a proximity sensor. The instrument have a height of 10 cm. Two ports in each sensor housing provide for connectivity, the upper port for air and the bottom port for water. Multiple instruments connected in series provide a precise water level and differences in readings between successive sensors provide for ground tilt to be resolved. Sensor resolution is 5 ?m per count and has a range of approximately 1.25 cm. Data output from each sensor is relayed to a Fermilab-constructed readout card that also has temperature/relative humidity and barometric pressure sensors connected. All data are relayed out of the mine by fiber optic cable and can be recorded by Ethernet at remote locations. The current arrays have been installed on the 2000-ft level (610 m) and consist of six instruments in each array. Three sensors were placed in a N-S oriented drift and three in an E-W oriented drift. Using this orientation, it is anticipated that tilt direction may be resolved in addition to overall tilt magnitude. To date the data show passage of earth tides and frequency analysis has revealed five components to this signal, three associated with the semi-diurnal (~12.4 hr) and two with the diurnal (~24.9 hr) tides. Currently, installation methods are being analyzed between concrete pillar and rib-mounting using the existing setup on the 2000-ft level. Using these results, two additional arrays of Fermilab instruments will be installed on the 4550-ft and 4850-ft levels (1387 and 1478 m, respectively). In addition to Fermilab instruments, several high resolution Budker tiltmeters (1 ?m resolution) will be installed in the mine workings in the near future, some correlated to Fermilab instruments (for comparative analysis) and others in independent arrays. All tiltmeter data will be analyzed with water reduction data (currently being collected from the #6 winze as the mine is dewatered) and data from rock stress/fracture experiments to document net ground settling due to dewatering, potential collapse of stope areas and renewed excavation activities.

Stetler, L. D.; Volk, J. T.

2009-12-01

179

Water levels in continuously monitored wells in the Yucca Mountain Area, Nevada, 1989  

International Nuclear Information System (INIS)

Water levels have been monitored hourly in 16 wells representing 24 intervals in the Yucca Mountain area, Nevada. Water levels were monitored using pressure transducers and were recorded by data loggers. The pressure transducers were periodically calibrated by raising and lowering them in the wells. The water levels were normally measured at approximately the same time that the transducers were calibrated. Where the transducer output appeared reasonable, it was converted to water levels using the calibrations and manual water-level measurements. The amount of transducer output that was converted to water levels ranged from zero for one interval to 100 percent for one interval. Fifteen of the wells were completed in Tertiary volcanic rocks and one well was completed in Paleozoic carbonate rocks. Each well monitored from one to four depth intervals. Water-level fluctuation caused by barometric pressure changes and earth tides were observed. Transducer output is presented in graphic form and, where appropriate, water-level altitude is presented in graphical and tabular form

180

Dramatic enhancement of capillary wave fluctuations of a decorated water surface  

International Nuclear Information System (INIS)

We have demonstrated by x-ray diffuse scattering that a bimolecular layer of a preformed three-tailed amphiphile, ferric stearate, drastically enhances capillary wave fluctuations on water surface due to a reduction in surface tension to 1 mN/m. The bimolecular layer is composed of molecules in symmetric configuration, on top of molecules in asymmetric configuration with ferric ions in contact with water. Unlike the usual Langmuir monolayers, this layer of molecules does not rupture under compression, but becomes thicker. This behavior mimics folding of a membrane on a liquid surface and is closely related to the cohesive interaction brought by the ferric ions. The low effective tension of this artificial membrane depends on the available area and reduces as the microscopic excess area increases

181

Monitoring system for reactor water level  

International Nuclear Information System (INIS)

Purpose: To enable accurate judgement for reactor water level by measuring flow rate, temperature, pressure and the like of coolants flowing in and out of a BWR type reactor. Constitution: Flow rate, temperature and pressure are measured for all of the coolants flowing in and out of a reactor. The flowing-out coolants are measured in both vapor phase and liquid phase. These data are inputted into a computer, in which they are calibrated in comparison with the indication of a level detector during normal operation, or coolant amount in the reactor and the energy in the reactor are calculated upon abnormal stage, and displayed on a Braun tube. (J.P.N.)

182

A Convective Model Conm That Simulates Solute Redistribution Caused by Water Table Fluctuations  

Directory of Open Access Journals (Sweden)

Full Text Available A study of the solute redistribution caused by water-table fluctuations in experimental packed columns of fine sand and a sandy clay loam soil using potassium chloride as a non-reactive tracer is modelled. With the water table initially at the soil surface, the redistribution of surface applied chloride down the profile was measured after the water table was lowered, then after it was raised again to the soil surface, and then after it was again lowered. In each case, sufficient time was allowed before measurements of chloride were made for the soil-water profile in the column to approach equilibrium conditions with the water table. A simple convection model (CONM was developed and used to simulate the chloride redistribution. This was compared with the LEACHM model of Wagenet and Hutson based on the convection-dispersion equation, and the physical basis of each critically discussed. It was found that the experimental results in general agreed better with simulated results using CONM than with those using LEACHM. It was concluded that the chloride movement observed in the experimental columns was dominantly convective. The application of this work to optimise fertiliser requirements when subirrigation-drainage systems are employed is discussed.

Cesáreo Landeros-Sánchez

2012-11-01

183

Fluctuation of TeV to EeV Energy Muons and Induced Muon Showers in Water  

OpenAIRE

By using the integral method in the muon propagation through water, we calculate the range fluctuation of high and ultra high energy muons. Many authors divide all radiative processes into two parts, namely, the continuous part and radiative part in their Monte Carlo simulation in order to consider the fluctuation in the both ranges and energies of the muons, while we treat all stochastic processes as exactly as possible, without the introduction of the continuous parts in a...

Okumura, Y.; Takahashi, N.; Misaki, A.

2010-01-01

184

Magnetization reversal and two level fluctuations by spin-injection in a ferromagnetic metallic layer  

CERN Document Server

Slow magnetic relaxation and two level fluctuations measurements under high current injection is performed in single-contacted ferromagnetic nanostructures. The magnetic configurations of the samples are described by two metastable states of the uniform magnetization. The current-dependent effective energy barrier due to spin-transfer from the current to the magnetic layer is measured. The comparison between the results obtained with Ni nanowires of 6 $\\mu $m length and 60 nm diameter, and Co (10 nm)/Cu (10 nm)/Co(30 nm) nanometric pillars of about 40 nm in diameter refined the characterization of this effect. It is shown that all observed features cannot be reduced to the action of a current dependent effective field. Instead, all measurements can be described in terms of an effective temperature, which depends on the current amplitude and direction. The system is then analogous to an unstable open system. The effect of current induced magnetization reversal is interpreted as the balance of spin injection be...

Wegrowe, J E

2003-01-01

185

Thermal fluctuation levels of magnetic and electric fields in unmagnetized plasma: The rigorous relativistic kinetic theory  

International Nuclear Information System (INIS)

Any fully ionized collisionless plasma with finite random particle velocities contains electric and magnetic field fluctuations. The fluctuations can be of three different types: weakly damped, weakly propagating, or aperiodic. The kinetics of these fluctuations in general unmagnetized plasmas, governed by the competition of spontaneous emission, absorption, and stimulated emission processes, is investigated, extending the well-known results for weakly damped fluctuations. The generalized Kirchhoff radiation law for both collective and noncollective fluctuations is derived, which in stationary plasmas provides the equilibrium energy densities of electromagnetic fluctuations by the ratio of the respective spontaneous emission coefficient and the true absorption coefficient. As an illustrative example, the equilibrium energy densities of aperiodic transverse collective electric and magnetic fluctuations in an isotropic thermal electron-proton plasmas of density ne are calculated as |?B|=?((?B)2)=2.8(nemec2)1/2g1/2?e7/4 and |?E|=?((?E)2)=3.2(nemec2)1/2g1/3?e2, where g and ?e denote the plasma parameter and the thermal electron velocity in units of the speed of light, respectively. For densities and temperatures of the reionized early intergalactic medium, |?B|=6·10?18G and |?E|=2·10?16G result

186

Water level simulation in bays by spatial interpolation of tidal constituents, residual water levels, and datums  

Science.gov (United States)

A new method of simulating total water level relative to a datum takes values at the tide gauges and spatially interpolates them throughout the region. The values at the gauges which are spatially interpolated are: (1) each tidal constituent's amplitude and (2) phase value; (3) the residual, or non-tidal, water level; and (4) the offset, which is either the difference between local mean sea level (MSL) and mean lower low water (MLLW), or a tidal datum (either MSL or MLLW) relative to the ellipsoid. The water level at any point is computed by summing the astronomic tide (computed from the interpolated constituents), the interpolated residual, and the interpolated offset. In addition, for a GPS-supported survey, the ellipsoidally referenced MLLW values can be spatially interpolated and used to determine MLLW depth. The spatial interpolation at the core of this method is carried out by the use of a set of weighting functions that quantify the local contribution from each of the shore gauges. The weighting functions are generated numerically by solving Laplace's equation on a grid. The new method of estimating total water levels relative to a datum is called tidal constituent and residual interpolation (TCARI). The TCARI method was tested for accuracy using post-processed kinematic GPS measurements of water level collected by NOS in Galveston Bay, Texas, and San Francisco Bay, California. The root mean square errors were estimated to be 8 cm for the Galveston Bay data and 9.2 cm for the San Francisco Bay data, which is approximately the error in the measurements.

Hess, Kurt

2003-03-01

187

Photon counting statistics of V-type three-level systems:The effects of the field fluctuations  

Science.gov (United States)

We investigate the influence of the field fluctuations to the emission photons of V-type three-level systems. The emission intensity I and Mandel's Q parameter show stochastic resonance with respect to the pure dephasing constant ?p. The amplitude fluctuation of the field causes these systems to lose their coherence. On the other hand, the amplitude fluctuation provides a new interference method for these systems. The quantum beats are shown in the orthogonal system. Project supported by the National Natural Science Foundation of China (Grand Nos. 91021009, 21073110, and 11374191), the Natural Science Foundation of Shandong Province, China (Grant No. ZR2013AQ020), the Postdoctoral Science Foundation of China (Grant No. 2013M531584), and the Doctoral Program of Higher Education of China (Grant Nos. 20130131110005 and 20130131120006).

Peng, Yong-Gang; Zheng, Yu-Jun

2015-02-01

188

Fluctuations in Species-Level Protein Expression Occur during Element and Nutrient Cycling in the Subsurface  

OpenAIRE

While microbial activities in environmental systems play a key role in the utilization and cycling of essential elements and compounds, microbial activity and growth frequently fluctuates in response to environmental stimuli and perturbations. To investigate these fluctuations within a saturated aquifer system, we monitored a carbon-stimulated in situ Geobacter population while iron reduction was occurring, using 16S rRNA abundances and high-resolution tandem mass spectrometry proteome measur...

Wilkins, Michael J.; Wrighton, Kelly C.; Nicora, Carrie D.; Williams, Kenneth H.; Mccue, Lee Ann; Handley, Kim M.; Miller, Chris S.; Giloteaux, Ludovic; Montgomery, Alison P.; Lovley, Derek R.; Banfield, Jillian F.; Long, Philip E.; Lipton, Mary S.

2013-01-01

189

Determination of the relative discharge rate from a uranium mine tailings pond by water level measurements  

International Nuclear Information System (INIS)

A method using water level measurements only was developed to determine the effectiveness of the revegetation or other selected materials as a seepage reducing agent for uranium mine tailings ponds. The effluence and thus the rate of the surface and subsurface water contamination around the tailings pond is directly proportional to the water head difference existing between the water tables inside and outside the pond. The method uses water level measurements taken before and after revegetation or taken simultaneously under revegetated and barren sections of the pond. Effluent rate variation of +- 1% can be detected with the measuring technique. For this reason the method is suitable for monitoring the fluctuation of the contamination rate from abandoned uranium mine tailing ponds. The method can predict the performance of the revegetation or other selected seepage reducing material before the commitment of any large expenditure

190

Paleoclimatic significance of lake level fluctuations in the Lahontan Basin. [Pyramid Lake, Nevada  

Energy Technology Data Exchange (ETDEWEB)

An energy flux balance model has been developed which treats evaporation as a function of air temperature, surface water temperature, precipitable water aloft, the amount, height, and type of sky cover, and the optical air mass. The model has been used to estimate the mean historical evaporation rate for Pyramid Lake, Nevada, using as input climatic data from the Reno area averaged over the period 1950 to 1975. Estimated and measured values of the mean annual evaporation rate were found to be in good agreement. The model was used to simulate changes in the level, the surface area and the volume of paleo Lake Lahontan. In particular, possible climatic states responsible for past high stands (1270 and 1330 m) were investigated. A conservative range of discharge values was used in the calculations. Results of the simulations indicate the fundamental importance of sky cover in the creation and destruction of large lake systems.

Benson, L.V.

1980-08-01

191

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

Science.gov (United States)

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) ? 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 ? to the ? 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 ? and SR% down the bog plateau (BP), bog margin (BM) and fen lagg (FL) cores in the Ryggmossen mire indicates that the sphagnum acid bound into the peat is being degraded in the unsaturated and seasonally-saturated layers. There is then a stabilisation of Sphagnum-derived phenols in the deepest horizons of the seasonally-saturated layer and into the permanently-saturated layer. These results suggest that "bound" sphagnum acid will be stabilised in peatlands shifting to a wetter and more variable precipitation regime whereas it will be gradually stripped away (e.g. by hydrolysis/enzymatic activity) in surficial peats shifting to a drier climate, such that any subsequent rewetting of the peat could lead to anaerobic hydrolysis and fermentation of the newly exposed carbohydrates. This highlights the sensitivity of Sphagnum surficial peats to climate-induced changes in water levels albeit there may be differences in the extent of degradation along the bog-fen gradient.

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

2013-04-01

192

Potential Effects of Climate Change on the Water Level, Flora and Macro-fauna of a Large Neotropical Wetland  

OpenAIRE

Possible consequences of climate change in one of the world’s largest wetlands (Ibera, Argentina) were analysed using a multi-scale approach. Climate projections coupled to hydrological models were used to analyse variability in wetland water level throughout the current century. Two potential scenarios of greenhouse gas emissions were explored, both resulting in an increase in the inter-annual fluctuations of the water level. In the scenario with higher emissions, projections also showed a...

U?beda, Ba?rbara; Di Giacomo, Adrian S.; Neiff, Juan Jose?; Loiselle, Steven A.; Guadalupe Poi, Alicia S.; Ga?lvez, Jose? A?ngel; Casco, Silvina; Co?zar, Andre?s

2013-01-01

193

Impact of scaled-down on dissolved oxygen fluctuations at different levels of the lipase synthesis pathway of Yarrowia lipolytica  

Directory of Open Access Journals (Sweden)

Full Text Available The impact of the fluctuations in dissolved oxygen tension (DOT on the lipase production by Yarrowia lipolytica has been investigated in a scale-down reactor (SDR. This bioreactor comprises a 20 l agitated vessel with an automatic valve controlling the opening and closure of the air flow line. This kind of scale-down apparatus is used in order to generate DOT gradients encountered in large-scale, while maintaining the other environmental conditions constant. The impact of DOT fluctuations has been estimated at three levels of the lipase synthesis machinery: lipase gene expression, lipase translation, lipase excretion to the extracellular medium. Among these levels, the performance of lipase production under oscillating DOT was significantly affected at the lipase gene expression level.

Delvigne, F.

2010-01-01

194

A novel Monte Carlo algorithm for polarizable force fields: Application to a fluctuating charge model for water  

International Nuclear Information System (INIS)

In this Monte Carlo algorithm for polarizable force fields, the fluctuating charges are treated as special degrees of freedom subject to a secondary low-temperature thermostat in close analogy to the extended Lagrangian formalism commonly used in molecular dynamics simulations of such systems. The algorithm is applied to Berne close-quote s SPC-FQ (simple point charge endash fluctuating charge) model for water. The robustness of the algorithm with respect to the temperature of the secondary thermostat and to the fraction of fluctuating-charge moves is investigated. With the new algorithm, the cost of Monte Carlo simulations using fluctuating-charge force fields increases by less than an order of magnitude compared to simulations using the parent fixed-charge force fields. copyright 1998 American Institute of Physics

195

Some Examples Of Water Resources Variability In The Context Of Climatic Fluctuations  

Science.gov (United States)

The determination of the impact of climate change on hydrological systems and their water resource constitutes a major stake of the 21st century to which the scientists must answer. First of all, it is necessary to understand how climate are expressed in the hydrosystems. For several years, the M2C laboratory of the University of Rouen has tried to answer this question by working within the framework of many regional, national and international programs as well as PhD works. Those studies involve analyses of hydrological systems located: (1) in various climatic and geomorphological contexts on both sides of the Atlantic Ocean, (2) in various hydrological compartments (surface and ground water), (3) at various spatial scales (watersheds smaller than 1000 km2 and large rivers). The approach consists in studying the long-term changes, oscillations and fluctuations of hydrologic variables by the analysis of time series (precipitation, discharge, piezometry), in particular by means of signal analysis and processing methods. The studied hydrosystems are small watersheds and aquifer in Haute- Normandie, the Seine river (NW France), north-african watersheds (W Morocco and N Algeria), small watersheds and aquifer in Texas, the Colorado river (Texas) and the Mississippi river. Although the identification of structured variations might be uneasy - sometimes just impossible - in raw data, wavelet analysis, for instance, makes it possible to detect localized energetic structures and possible periodicities in all the studied hydrosystems and to quantify them. In many surface hydrosystems we note an intensification of the annual energy band which corresponds to the hydrological cycle. In the NW of France and North Africa, we observe 2-3-year and 5-7-year modes which could be linearly related to fluctuations in the NAO using wavelet coherence. In the USA, we notice similar 2- 3-year and 5-7-year modes that might be possibly related to the characteristic 2-4-year and 4-8-year of SOI. In any case, two major temporal discontinuities were systematically recovered around the 1970's and the 1990's characterized respectively by the occurrence of the 5-7-year and 2-3-year peaks. The above- mentioned intensification of the hydrological cycle is observed from 1990 up to now. These results would describe a global pattern in hydrological processes as a response to climate fluctuations.

Laignel, B.; Massei, N.; Rossi, A.; Mesquita, J.; Slimani, S.

2008-12-01

196

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies  

International Nuclear Information System (INIS)

Water–tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with xTBA ? 0.03–0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at xTBA ? 0.05. We note that “islands” of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, xTBA ? 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level

197

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies  

Energy Technology Data Exchange (ETDEWEB)

Water–tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with x{sub TBA} ? 0.03–0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at x{sub TBA} ? 0.05. We note that “islands” of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, x{sub TBA} ? 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level.

Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman, E-mail: bbagchi@sscu.iisc.ernet.in [SSCU, Indian Institute of Science, Bangalore 560012 (India)

2014-05-21

198

Development of heater-and-thermocouple-type water level sensor  

International Nuclear Information System (INIS)

In the Fukushima-Daiichi Nuclear Power Plant Accident, the measurements of water level in pressure vessel and spent fuel pool was impossible due to station blackout, and it resulted in difficulty for countermeasures against the accidents and for understanding of the situations of reactor core after accidents. Therefore, we started to develop a new water level sensor for spent fuel pool with high reliability, which works with low power voltage. This report describes reviews of conventional water level sensor and design and production of new water level sensor. After production of the sensor, performance tests were performed at the water temperature between room temperature and 95degC, and the it was confirmed that the sensor is able to measure water level with the accuracy of ±20mm. As the results, a perspective to use the new water level sensor as water level gauge for spent fuel pool and reactor vessels after severe accident is acquired. (author)

199

Sub-centennial Holocene fluctuations of surface water masses in the western Barents Sea  

Science.gov (United States)

The North Atlantic Current (NAC) brings warm and saline water into the Arctic, and the inflow is balanced by the outflow of cold surface water and by the formation of deep water to the south. This is part of the Atlantic Meridional Overturning Circulation (AMOC). Changes of the AMOC can greatly affect the global ocean circulation and climate, especially at high latitudes where the inflow of warm water and heat exchange is essential for environment and society. Hence, it is crucial to establish the natural range of oceanographic fluctuations within this area. Here we investigate a continuous high resolution record from the Kveithola Through, western Barents Sea in order to elucidate the past variability of the flow of Atlantic Water during the Holocene. The results are compared to existing records north and south of our study site in order to map regional changes of the inflow of Atlantic Water. The age model has been based on ten AMS C14 dates, and show sediment accumulation rates up to 0.034 mm/yr, enabling a sub-centennial resolution.The samples have been analyzed for their planktic foraminiferal faunal distribution. In addition analyses of stable isotopes (d18O, d13C) and Mg/Ca ratios will also be carried out further quantifying the surface water mass properties as SST and SSS. Finally, analyses of shell weights and fragments will be presented in order to evaluate the degree of preservation of the current paleoceanographic record. Preliminary results show a planktic foraminiferal fauna consisting of two dominating species: the polar N. pachyderma sinistral and the sub-polar T. quinqueloba. The early Holocene records a relative distribution between 50 and 60 % of N. pachyderma sinistral, while throughout the mid and late Holocene T. quinqueloba dominates the fauna with values up to 75%. Further, several other species, such as N. incompta, G. glutinata, G. bulloides and G. uvula, are found less abundantly. During the last 1000 years G. uvula shows a remarkable increase, possibly indicating an advanced fresh water input. The results of this studyconfirm a south-north time transgressive onset of Holocene warming as previously recorded in the region. However this study finds a general higher frequency ofT. quinquelobareflecting a very close position to the Arctic Front.

Berben, S.; Husum, K.; Hald, M.

2012-04-01

200

Observing plants dealing with soil water stress: Daily soil moisture fluctuations derived from polymer tensiometers  

Science.gov (United States)

Periods of soil water deficit often occur within a plant's life cycle, even in temperate deciduous and rain forests (Wilson et al. 2001, Grace 1999). Various experiments have shown that roots are able to sense the distribution of water in the soil, and produce signals that trigger changes in leaf expansion rate and stomatal conductance (Blackman and Davies 1985, Gollan et al. 1986, Gowing et al. 1990 Davies and Zhang 1991, Mansfield and De Silva 1994, Sadras and Milroy 1996). Partitioning of water and air in the soil, solute distribution in soil water, water flow through the soil, and water availability for plants can be determined according to the distribution of the soil water potential (e.g. Schröder et al. 2013, Kool et al. 2014). Understanding plant water uptake under dry conditions has been compromised by hydrological instrumentation with low accuracy in dry soils due to signal attenuation, or a compromised measurement range (Whalley et al. 2013). Development of polymer tensiometers makes it possible to study the soil water potential over a range meaningful for studying plant responses to water stress (Bakker et al. 2007, Van der Ploeg et al. 2008, 2010). Polymer tensiometer data obtained from a lysimeter experiment (Van der Ploeg et al. 2008) were used to analyse day-night fluctuations of soil moisture in the vicinity of maize roots. To do so, three polymer tensiometers placed in the middle of the lysimeter from a control, dry and very dry treatment (one lysimeter per treatment) were used to calculate water content changes over 12 hours. These 12 hours corresponded with the operation of the growing light. Soil water potential measurements in the hour before the growing light was turned on or off were averaged. The averaged value was used as input for the van Genuchten (1980) model. Parameters for the model were obtained from laboratory determination of water retention, with a separate model parameterization for each lysimeter setup. Results show daily fluctuations in water content changes, with both root water uptake and root water excretion. The magnitude of the water content change was in the same order for all treatments, thus suggesting compensatory uptake. References Bakker G, Van der Ploeg MJ, de Rooij GH, Hoogendam CW, Gooren HPA, Huiskes C, Koopal LK and Kruidhof H. New polymer tensiometers: Measuring matric pressures down to the wilting point. Vadose Zone J. 6: 196-202, 2007. Blackman PG and Davies WJ. Root to shoot communication in maize plants of the effects of soil drying. J. Exp. Bot. 36: 39-48, 1985. Davies WJ and Zhang J. Root signals and the regulation of growth and development of plants in drying soil. Annu. Rev. Plant Physiol. Plant Mol. Biol. 42: 55-76, 1991. Gollan T, Passioura JB and Munns R. Soil water status affects the stomatal conductance of fully turgid wheat and sunflower leafs. Aust. J. Plant Physiol. 13: 459-464, 1986. Gowing DJG, Davies WJ and Jones HG. A Positive Root-sourced Signal as an Indicator of Soil Drying in Apple, Malus x domestica Borkh. J. Exp. Bot. 41: 1535-1540, 1990. Grace J. Environmental controls of gas exchange in tropical rain forests. In: Press, M.C, J.D. Scholes and M.G. Barker (ed.). Physiological plant ecology: the 39th Symposium of the British Ecological Society. Blackwell Science, United Kingdom, 1999. Kool D, Agam N, Lazarovitch N, Heitman JL, Sauer TJ, Ben-Gal A. A review of approaches for evapotranspiration partitioning. Agricultural and Forest Meteorology 184: 56- 70, 2014. Mansfield TA and De Silva DLR. Sensory systems in the roots of plants and their role in controlling stomatal function in the leaves. Physiol. Chem. Phys. & Med. 26: 89-99, 1994. Sadras VO and Milroy SP. Soil-water thresholds for the responses of leaf expansion and gas exchange: a review. Field Crops Res. 47: 253-266, 1996. Schröder N, Lazarovitch N, Vanderborcht J, Vereecken H, Javaux M. Linking transpiration reduction to rhizosphere salinity using a 3D coupled soil-plant model. Plant Soil 2013, doi: 10.1007/s11104-013-1990-8 Van der Ploeg MJ, Gooren HPA, Bakker G and de Rooij GH.

van der Ploeg, Martine; de Rooij, Gerrit

2014-05-01

201

[Diurnal fluctuations of blood lipids and sugar level in healthy persons and in patients with ischemic heart diseases].  

Science.gov (United States)

Diurnal fluctuations in the level of cholesterol, phospholipids, triglycerides, NEFA and sugar in the blood of practically healthy subjects and in patients with ischemic heart disease, attended by hyperlipoproteinemia of the II and IV types, were studied. Investigations were made at 9 a.m., 3 and 9 p.m. The variations of the lipid fractions and sugar in the blood of practically healthy individuals and of patients with hyperlipoproteinemia showed no essential differences. There were minimal diurnal changes in the cholesterol level, a tendency towards an increase in the level of phospholipids, a statistically significant rise in the content of triglycerides and sugar in the blood and large fluctuations in the level of the NEFA, both upwards and downwards. In patients with hyperlipoproteinemia of the II type variations in the blood cholesterol and phospholipids levels occurring in the course of the day proved to be of the same nature as in the case of normal lipoproteinemia, with no diurnal rise of the sugar level, while the NEFA content showed a distinct upward tendency. In patients it was only the blood cholesterol and triglycerides level that remained at a statistically significant higher level throughout the day. PMID:1123884

Krivoruchenko, I V; Ianushkene, T S

1975-02-01

202

Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this paper was to use quantitative systems-level approach employing biotic ligand model based threshold damage model to examine physiological responses of tilapia and freshwater clam to sequential pulsed and fluctuating arsenic concentrations. We tested present model and triggering mechanisms by carrying out a series of modeling experiments where we used periodic pulses and sine-wave as featured exposures. Our results indicate that changes in the dominant frequencies and pulse timing can shift the safe rate distributions for tilapia, but not for that of freshwater clam. We found that tilapia increase bioenergetic costs to maintain the acclimation during pulsed and sine-wave exposures. Our ability to predict the consequences of physiological variation under time-varying exposure patterns has also implications for optimizing species growing, cultivation strategies, and risk assessment in realistic situations. - Systems-level modeling the pulsed and fluctuating arsenic exposures.

Chen, W.-Y. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Tsai, J.-W. [Institute of Ecology and Evolutionary Ecology, China Medical University, Taichung 40402, Taiwan (China); Ju, Y.-R. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Liao, C.-M., E-mail: cmliao@ntu.edu.t [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2010-05-15

203

Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam  

International Nuclear Information System (INIS)

The purpose of this paper was to use quantitative systems-level approach employing biotic ligand model based threshold damage model to examine physiological responses of tilapia and freshwater clam to sequential pulsed and fluctuating arsenic concentrations. We tested present model and triggering mechanisms by carrying out a series of modeling experiments where we used periodic pulses and sine-wave as featured exposures. Our results indicate that changes in the dominant frequencies and pulse timing can shift the safe rate distributions for tilapia, but not for that of freshwater clam. We found that tilapia increase bioenergetic costs to maintain the acclimation during pulsed and sine-wave exposures. Our ability to predict the consequences of physiological variation under time-varying exposure patterns has also implications for optimizing species growing, cultivation strategies, and risk assessment in realistic situations. - Systems-level modeling the pulsed and fluctuating arsenic exposures.

204

A two-dimensional analytical model describing groundwater level fluctuations in an anisotropic and bending leaky aquifer system near estuary  

Science.gov (United States)

Tide-induced head fluctuation in a two-dimensional estuarine aquifer system is complicated and rather important in dealing with many groundwater management or remediation problems. The conceptual model of the aquifer system we considered is anisotropic, multi-layered with a bending estuarine bank, and subject to the tidal fluctuation effects from both the sea shore and estuarine river. The solution of the model describing the groundwater head distribution in such a coastal aquifer system is developed based on the method of separation of variables and a coordinate transformation applied to the river boundary at the bend with an angle of arbitrary degree to the line perpendicular to the sea shore. The solutions by Sun (Sun H. A two-dimensional analytical solution of groundwater response to tidal loading in an estuary, Water Resour. Res. 1997; 33:1429-35) as well as Tang and Jiao (Tang Z. and J. J. Jiao, A two-dimensional analytical solution for groundwater flow in a leaky confined aquifer system near open tidal water, Hydrological Processes, 2001; 15: 573-585) can be shown to be special cases of the present solution if the degree of the bending angle is zero. On the basis of the analytical solution, the groundwater head distribution in response to estuarine boundary is examined and the influences of anisotropy, leakage, hydraulic parameters, and bending angle on the groundwater head fluctuation are investigated and discussed.

Yeh, Hund-Der; Chuang, Mo-Hsiung

2014-05-01

205

Entanglement between a pair of spatially separated two-level atoms induced by zero-point field fluctuations  

CERN Document Server

We have considered the interaction of a pair of spatially separated two-level atoms with the electromagnetic field in its vacuum state and we have analyzed the amount of entanglement induced between the two atoms by the non local field fluctuations. This has allowed us to characterize the quantum nature of the non local correlations of the electromagnetic field vacuum state as well as to link the induced quantum entanglement with Casimir-Polder potentials.

Cirone, M A; Palma, G M; Passante, R; Persico, F S; Cirone, Markus.A.; Compagno, Giuseppe; Passante, Roberto; Persico, Francesco S.

2004-01-01

206

Soil migration and plant uptake of technetium from a fluctuating water table  

International Nuclear Information System (INIS)

Soil columns (50 x 15 cm) were used to determine the potential for 95mTc (as a surrogate for 99Tc which is an important component of some radioactive waste) to migrate from a contaminated, fluctuating water table, through sandy loam soil and into perennial ryegrass. Upward migration was significantly retarded with, generally, only the bottom few centimetres of soil becoming contaminated over the 6 months of the experiment. This is thought to have been due to the presence of anoxic conditions within the water table leading to the reduction of pertechnetate to TcIV species which are relatively insoluble. However, some evidence of very slow upward migration over time was found. Only a small and inconsistent transfer of activity into the perennial ryegrass was observed. Whilst these observations would suggest that 99Tc is less important than radionuclides such as 129I and 36Cl in terms of the risk associated with radioactive waste disposal, the potential for a slow upward migration, and/or a pulse-release following the re-oxidation of reduced soil in which 99Tc has accumulated should not be overlooked

207

On the applicability of available methods for estimating daily evapotranspiration by using diurnal water table fluctuations  

Science.gov (United States)

Shallow groundwater is mainly discharged by phreatophytes in many riparian ecosystems of arid and semiarid environment, while estimation of groundwater evapotranspiration (ETG) in these regions still remains a challenge for regional water resources assessment. Since White (1932) provided a method for estimating ETG based on diurnal groundwater dynamics, a number of modifications of White method were developed for calculating ETG; however, a major source of uncertainty in all these methods is associated with estimates groundwater recovery rate. In this study, we developed a criterion of quasi-steady conditions of groundwater evapotranspiration processes, which based on a coupled consideration of the water and energy balance. This criterion was tested by using the one dimensional saturated-unsaturated flow model, and use of these guidelines with the White method approaches could enable minimize uncertainty in estimating ETG. The developed methodology is illustrated by estimation of ETG rate using high-accuracy monitoring data of groundwater fluctuations for Goby environments in a typical arid region of northwest China.

Wang, P.; Pozdniakov, S. P.; Lekhov, M.; Yu, J.

2012-12-01

208

Historical impact of water infrastructure on water levels of the Mekong River and the Tonle Sap system  

Science.gov (United States)

The rapid rate of water infrastructure development in the Mekong Basin is a cause for concern due to its potential impact on fisheries and downstream natural ecosystems. In this paper, we analyze the historical water levels of the Mekong River and Tonle Sap system by comparing pre- and post-1991 daily observations from six stations along the Mekong mainstream from Chiang Saen (northern Thailand), to Stung Treng (Cambodia), and the Prek Kdam station on the Tonle Sap River. Observed alterations in water level patterns along the Mekong are linked to temporal and spatial trends in water infrastructure development from 1960 to 2010. We argue that variations in historical climatic factors are important, but they are not the main cause of observed changes in key hydrological indicators related to ecosystem productivity. Our analysis shows that the development of mainstream dams in the upper Mekong Basin in the post-1991 period may have resulted in a modest increase of 30-day minimum levels (+17%), but significant increases in fall rates (+42%) and the number of water level fluctuations (+75%) observed in Chiang Saen. This effect diminishes downstream until it becomes negligible at Mukdahan (northeast Thailand), which represents a drainage area of over 50% of the total Mekong Basin. Further downstream at Pakse (southern Laos), alterations to the number of fluctuations and rise rate became strongly significant after 1991. The observed alterations slowly decrease downstream, but modified rise rates, fall rates, and dry season water levels were still quantifiable and significant as far as Prek Kdam. This paper provides the first set of evidence of hydrological alterations in the Mekong beyond the Chinese dam cascade in the upper Mekong. Given the evident alterations at Pakse and downstream, post-1991 changes could also be directly attributed to water infrastructure development in the Chi and Mun basins of Thailand. A reduction of 23 and 11% in the water raising and falling rates respectively at Prek Kdam provides evidence of a diminished Tonle Sap flood pulse in the post-1991 period. Given the observed water level alterations from 1991 to 2010 as a result of water infrastructure development, we can extrapolate that future development in the mainstream and the key transboundary Srepok, Sesan, and Sekong sub-basins will have an even greater effect on the Tonle Sap flood regime, the lower Mekong floodplain, and the delta.

Cochrane, T. A.; Arias, M. E.; Piman, T.

2014-11-01

209

Soil- and plant- water uptake in saline environments and their consequences to plant adaptation in fluctuating climates  

Science.gov (United States)

Ecological processes determining plant colonization are quite peculiar and competition among different species is governed by a set of unique adaptations to stress conditions caused by drought, hypoxic or hyper-saline conditions. These adaptations and possible positive feedbacks often lead to the formation of patterns of vegetation colonization and spatial heterogeneity (zonation), and play a primary role in the stabilization of sediments. It is these issues that frame the scope of this study. The main objective of this work is to track one of the fundamental pathways between plant adaptation (quantified in terms of physiological and ecological attributes such as leaf area or root density profile) and feedbacks (quantified by plant-mediated alterations to water availability and salinity levels): root water uptake. Because root-water uptake is the main conduit connecting transpiring leaves to reservoirs of soil water, the means by which salinity modifies the processes governing its two end-points and any two-way interactions between them serves as a logical starting point. Salinity effects on leaf transpiration and photosynthesis are first explored via stomatal optimization principles that maximize carbon gain at a given water loss for autonomous leaves. Salinity directly affects leaf physiological attributes such as mesophyll conductance and photosynthetic parameters and hence over-all conductance to transpiration as well as different strategies to cope with the high salinity (e.g. through salt seclusion, compartmentation and osmotic adjustments). A coupled model of subsurface flow based on a modified Richards’ equation that accounts for the effects of increasing salinity, anaerobic conditions, water stress and compensation factors is developed. Plant water uptake is considered as a soil moisture sink term with a potential rate dictated by the carbon demands of the leaves, and an actual rate that accounts for both - hydraulic and salinity limitations. Using this model, the root distribution shape function (e.g. constant, linear, exponential, or power-law) that optimally satisfies these carbon demands and simultaneous hydraulic and salinity constraints of the soil-root system is then determined for a set of forcing variables and boundary conditions. Adaptation speeds and feedback strengths to future climatic fluctuations are explored as ‘departures’ from this equilibrium profile state.

Volpe, V.; Albertson, J. D.; Katul, G. G.; Marani, M.

2010-12-01

210

U(VI) transport under the condition of water table fluctuations  

Science.gov (United States)

U(VI) transport at the 300 Area Hanford IFRC site, WA appears to be strongly related to water table fluctuations resulting from rapid changes of Column River stage. In the “smear zone” (zone through which the water table sweeps) at the IFRC site, sediment can experience more than one saturation cycle every day. This unique phenomenon complicates the current understanding of U(VI) transport because the smear zone is likely a persistent source of long-term U(VI) contamination. In our study, two comparison column (4.28 cm × 44.4 cm) experiments are conducted to exam the U(VI) desorption affected by occasional, partially unsaturated conditions. In the experiment, one column remains saturated and the other one experiences three saturation-desaturation cycles. Less than 8 mm composite sediments collected from the Hanford IFRC site are packed into the column. TDRs and tensiometers are built into the column to measure both water contents and metric potentials at different depths. U-free synthetic ground water (SGW) is used to desorb U(VI) in both columns. In the experiment, both columns are initially saturated and SGW is injected in at a constant rate to desorb U(VI). Three stop flow events are embedded into desorption. Before each stop flow event, one of the columns is freely drained and the sediment represents the smear zone with the water table at the bottom of the column. After each stop flow, the column is re-saturated and regular desorption continues in both columns. During desorption and drainage, the pH in the effluent is continuously monitored. In addition, U(VI), major ions and alkalinity are measured in all samples. Previous studies show that aqueous U(VI) concentration increases due to the kinetic behavior of U(VI) desorption. If the column remains unsaturated during the stop flow, it is expected that the kinetic behavior of U(VI) will cause a much higher U(VI) concentration in less mobile pore water . Therefore, a lower U(VI) spike and a longer U(VI) tail in the breakthrough curve (after the stop flow) can be observed due to rate-limited mass transfer. A reactive transport model (STOMP) coupled with a multirate surface complexion model will be used to simulation the results and quantify the transport parameters. The calibrated model is expected to partially explain the long-term U(VI) plume in the 300 Area.

Yin, J.; Haggerty, R.; Rockhold, M. L.; Kent, D. B.; Istok, J. D.; Zachara, J. M.

2010-12-01

211

Redistribution of contaminants by a fluctuating water table in a micro-porous, double-porosity aquifer: field observations and model simulations.  

Science.gov (United States)

Large seasonal fluctuations of the water table are characteristic of aquifers with a low specific yield, including those fractured, double-porosity aquifers that have significant matrix porosity containing virtually immobile porewater, such as the Chalk of northern Europe. Where these aquifers are contaminated, a strong relationship between water table elevation and contaminant concentration in groundwater is commonly observed, of significance to the assessment, monitoring, and remediation of contaminated groundwater. To examine the processes governing contaminant redistribution by a fluctuating water table within the 'seasonally unsaturated zone', or SUZ, profiles of porewater solute concentrations have been established at a contaminated site in southern England. These profiles document the contaminant distribution in porewater of the Chalk matrix over the SUZ at a greater level of detail than recorded previously. A novel double-porosity solute transport code has been developed to simulate the evolution of the SUZ matrix porewater contaminant profiles, given a fluctuating water table, when the groundwater is initially contaminated and the SUZ is initially free of contamination. The model is simply characterised by: the matrix-fracture porosity ratio, the matrix block geometry, and a characteristic diffusion time. De-saturation and re-saturation of fractures is handled by a new approximation method. Contaminant accumulates in the upper levels of the SUZ, where it is less accessible to mobile groundwater, and acts as a persistent secondary source of contamination once the original source of contamination has been removed or has become depleted. The 'SUZ process' first attenuates the progress of contaminants in groundwater, and subsequently controls the slow release of contamination back to the mobile groundwater, thus prolonging the duration of groundwater contamination by many years. The SUZ process should operate in any fractured, micro-porous lithology e.g. fractured clays and mudstones, making this approach widely applicable. PMID:15949606

Fretwell, B A; Burgess, W G; Barker, J A; Jefferies, N L

2005-06-01

212

Development of reactor water level sensor for extreme conditions  

International Nuclear Information System (INIS)

In the Fukushima accident, measurement failure of water level was one of the most important factors which caused serious situation. The differential pressure type water level indicators are widely used in various place of nuclear power plant but after the accident of TMI-2, the need of other reliable method has been required. The BICOTH type and the TRICOTH type water level indicator for light water power reactors had been developed for in-pile water level indicator but currently those are not adopted to nuclear power plant. In this study, the development of new type water level indicator composed of thermocouple and heater is described. Demonstration test and characteristic evaluation of the water level indicator were performed and we had obtained satisfactory results. (author)

213

Water levels in the Yucca Mountain area, Nevada, 1993  

International Nuclear Information System (INIS)

Water levels were monitored in 28 wells in the Yucca Mountain area, Nevada, during 1993. Seventeen wells were monitored periodically, generally on a monthly basis, and 11 wells representing 18 intervals were monitored hourly. All wells monitor water levels in Tertiary volcanic rocks, except one that monitors water levels in Paleozoic carbonate rocks. Water levels were measured using calibrated steel tapes and pressure transducers; steel-tape measurements were corrected for mechanical stretch, thermal expansion, and borehole deviation to obtain precise water-level altitudes. Water-level altitudes in the Tertiary volcanic rocks ranged from about 728 meters above sea level east of Yucca Mountain to about 1,034 meters above sea level north of Yucca Mountain. Water-level altitudes in the well monitoring the Paleozoic carbonate rocks varied between 752 and 753 meters above sea level during 1993. Water levels were an average of about 0.04 meter lower than 1992 water levels. All data were acquired in accordance with a quality-assurance program to support the reliability of the data

214

Historical impact of water infrastructure on water levels of the Mekong River and the Tonle Sap System  

Directory of Open Access Journals (Sweden)

Full Text Available The rapid rate of water infrastructure development in the Mekong basin is a cause for concern due to its potential impact on fisheries and downstream natural ecosystems. In this paper we analyse the historical water levels of the Mekong River and Tonle Sap system by comparing pre and post 1991 daily observations from six stations along the Mekong mainstream from Chiang Sean (northern Laos, to Stung Treng (Cambodia, and the Prek Kdam station on the Tonle Sap River. Observed alterations in water level patterns along the Mekong are linked to temporal and spatial trends in water infrastructure development from 1960 to 2010. We argue that variations in historical climatic factors are important, but they are not the main cause of observed changes in key hydrological indicators related to ecosystem productivity. Our analysis shows that the development of mainstream dams in the upper Mekong basin in the post-1991 period have resulted in a significant increase of 7 day minimum (+91.6%, fall rates (+42%, and the number of water level fluctuations (+75 observed in Chiang Sean. This effect diminishes downstream until it becomes negligible at Mukdahan (northeast Thailand, which represents a drainage area of over 50% of the total Mekong Basin. Further downstream at Pakse (southern Laos, alterations to the number of fluctuations and rise rate became strongly significant after 1991. The observed alterations slowly decrease downstream, but modified rise rates, fall rates, and dry season water levels were still quantifiable and significant as far as Prek Kdam. This paper provides the first set of evidence of hydrological alterations in the Mekong beyond the Chinese dam cascade in the upper Mekong. Given the evident alterations with no precedence at Pakse and downstream, post-1991 changes can also be directly attributed to water infrastructure development in the Chi and Mun basins of Thailand. A reduction of 23 and 11% in the water raising and fall rates respectively at Prek Kdam provides evidence of a diminished Tonle Sap flood pulse in the post-1991 period. Given the observed water level alterations from 1991 to 2010 as a result of water infrastructure development, we can extrapolate that future development in the mainstream and the key transboundary Srepok, Sesan and Sekong subbasins will have an even greater effect on the Tonle Sap flood regime, the lower Mekong floodplain, and the delta.

T. A. Cochrane

2014-04-01

215

The effect of wind speed fluctuations on the performance of a wind-powered membrane system for brackish water desalination  

OpenAIRE

A wind-powered reverse osmosis membrane (wind-membrane) system without energy storage was tested using synthetic brackish water (2750 and 5500 mg/L NaCl) over a range of simulated wind speeds under both steady-state and fluctuating conditions. The parameters varied were: i) average wind speed from 3.7 (system start-up) to 8.7 m/s; ii) wind turbulence intensity from 0.0 (steady-state conditions) to 0.6 (extreme fluctuations); and iii) period of oscillation from 15 to 90 s. With ...

Park, Gavin L.; Scha?fer, Andrea; Richards, Bryce S.

2011-01-01

216

Effects of water level regulation on littoral zone of lakes Konnivesi and Ruotsalainen  

International Nuclear Information System (INIS)

Measures to develop an ecologically based regulation practice for the lakes Ruotsalainen and Konnivesi which belong to the Kymijoki watercourse, were undertaken in 1995, when the intermunicipal board for the Heinola health care centre and Myllykoski Oy proposed that the regulation licence should re-evaluated. The purpose of this study, which is part of the overall development project, was to assess the ecological impacts of regulation on the littoral zones of these lakes. More specifically, the study focussed on the changes in the ecology of the littoral zone due to the water level fluctuation. The littoral vegetation of lake Konnivesi reflects the improvement of water quality over the past fifteen years. The species indicative of eutrophication have mostly disappeared. The vegetation of the uppermost littoral zone has stabilised, and the effect of wave erosion is small Ice pressure on the bottom has hardly any impact on the plants sensitive to the ice scouring effect, because the ice-covered zone has actually been reduced in size consequent to the regulation. Owing to the small range of water level fluctuation during the open water period, the uppermost littoral zone remains very narrow, which restricts the spreading of especially helophytic vegetation. The narrow littoral zone impairs the development of the normal zonal biotope in many places and simultaneously prevents diverse increase of littoral biota. The aim of the ecological regulation practice proposed for Koogical regulation practice proposed for Konnivesi is to ensure a water level favourable for pike spawning It is further proposed that the water level should decline by 25 cm during the open water period following the flood peak. This would help to widen the littoral zone suited to helophytic vegetation and to increase the vegetational diversity of especially gently sloping shores. (orig.) 12 refs

217

Fluctuation Studies at the Subnuclear Level of Matter: Evidence for Stability, Stationarity and Scaling  

CERN Document Server

It is pointed out that the concepts and methods introduced by Bachelier and by Mandelbrot to Finance and Economics can be used to examine the fluctuations observed in high-energy hadron production processes. Theoretical arguments and experimental evidences are presented which show that the relative variations of hadron-numbers between successive rapidity intervals are non-Gaussian stable random variables, which exhibit stationarity and scaling. The implications of the obtained results are discussed.

Liu, Q

2003-01-01

218

Automatic radioisotopic control of water level in scrubber  

International Nuclear Information System (INIS)

Described is the system of continuous contactless automatic control of water level in scrubbers of blast furnace gas purification on the basis of tracking radiometric level indicators. The system permits to obtain the constant reliable information on water level in scrubber, it excludes completely possible accident situations and permits the personnel to step in the process of purification of blast furnace gas

219

Effects of Water Levels on Productivity of Canada Geese in the Northern Flathead Valley, Final Report.  

Energy Technology Data Exchange (ETDEWEB)

The Fish and Wildlife Program of the Northwest Power Planning Council calls for wildlife mitigation at hydroelectric projects in the Columbia River System. Beginning April, 1984, the Bonneville Power Administration funded a study of the effects of the operation of Hungry Horse and Kerr Dams on the western Canada goose (Branta canadensis moffittii) inhabitating the Flathead Valley of northwest Montana. The study was conducted by personnel of the Montana Department of Fish, Wildlife and Parks (MDFWP), to: (1) identify the size and productivity of this population, (2) identify current habitat conditions and losses of nesting and brood-rearing areas, (3) describe the effects of water level fluctuations on nesting and brood-rearing, and (4) identify mitigation alternatives to offset these effects. Annual pair and nest surveys were used to document the location and fate of goose nests. The number of known nesting attempts varied from 44 in 1984 to 108 in 1985, to 136 in 1986 and 134 in 1987. Fifty-four percent of the annual meeting nesting effort took place on elevated sites which were secure from the flooding and dewatering effects of fluctuating water levels. An average of 15 nests were found on stumps in the remnant Flathead River delta, however, an area strongly influenced by the operation of Kerr Dam. Annual nest losses to flooding and predation attributable to fluctuations caused by the dam were recorded. 53 refs., 24 figs., 35 tabs.

Casey, Daniel

1987-08-01

220

Arsenic in Well Water Can Raise Level in Baby Formula  

Science.gov (United States)

... sharing features on this page, please enable JavaScript. Arsenic in Well Water Can Raise Level in Baby ... 2015) Monday, February 23, 2015 Related MedlinePlus Pages Arsenic Drinking Water Infant and Newborn Nutrition MONDAY, Feb. ...

221

An Analysis of Historical Impacts of Water Resources Development on Water Levels of the Mekong River (Invited)  

Science.gov (United States)

The rapid rate of water resources development in the Mekong basin of Southeast Asia is a cause for concern due to potential impacts on highly valued fisheries and natural ecosystems. Historical water levels of the Mekong were analyzed by comparing pre and post 1991 daily data of 6 stations along the mainstream from Chiang Sean, in northern Lao PDR and Thailand, to Stung Treng, in Cambodia, and the Pre Kdam station near the Tonle Sap Lake in the lower Mekong floodplain using the Indicators of Hydrological Alteration (IHA) software. The year 1991 marks a turning point in the rate of development in the basin, with the start of development of mainstream dams in the upper Mekong and accelerated hydropower and irrigation development in key tributaries. Observed changes in water level patterns along the Mekong were linked to temporal and spatial water resources development from 1960 to 2010. Variations in climate were accounted for and are important, but they were not observed to be the main causes of changes in key hydrological indicators related to ecosystem productivity. The development of mainstream dams in the upper Mekong basin in the post 1991 period resulted in a significant change of seasonal water levels, raise rates, fall rates, and the number of water level fluctuations at Chiang Sean. This effect diminishes downstream until it becomes negligible at the Mukdahan monitoring station in Thailand, which represents a drainage area of over 50% of the total Mekong Basin. Further downstream at Pakse station in Southern Lao PDR, changes in hydrological indicators post 1991 were observed to be significant again, which can be directly attributed to water resource development in the Chi and Mun River basins in Northeastern Thailand. A reduction of 23% and 11% in water level raising rates and fall rates, respectively at Prek Kdam, provides clear evidence of a diminished flood pulse of the Tonle Sap Lake in the post 1991 period. Given the observed water level alterations from 1991 to 2010 as a result of water infrastructure development, we can extrapolate that future proposed development in the key transboundary Srepok, Sesan and Sekong basins of the Lower Mekong will have an even greater effect on the flood pulse of the Tonle Sap. Although much focus has been placed on impacts of mainstream dams in the upper Mekong, our analysis clearly shows that tributary development in the lower Mekong has already affected water level patterns significantly, particularly in the dry season. Through subsequent modeling we infer how future development could further impact water flows and livelihoods, and thus improve regional impact assessments. The analysis and methods can be translated to other river systems around the world undergoing rapid water resources development.

Cochrane, T. A.; Arias, M. E.; Piman, T.

2013-12-01

222

Water levels in the Yucca Mountain Area, Nevada, 1996  

International Nuclear Information System (INIS)

Water levels were monitored in 24 wells in the Yucca Mountain area, Nevada, during 1996. Twenty-two wells representing 28 depth intervals were monitored periodically, generally on a monthly basis, and 2 wells representing 3 depth intervals were monitored both hourly and periodically. All wells monitor water levels in Tertiary volcanic rocks except one that monitors water levels in paleozoic carbonate rocks. Water levels were measured using either calibrated steel tapes or a pressure sensor. Mean water-level altitudes in the Tertiary volcanic rocks ranged from about 727.86 to about 1,034.58 meters above sea level during 1996. The mean water-level altitude in the well monitoring the Paleozoic carbonate rocks was about 752.57 meters above sea level during 1996. Mean water-level altitudes for 1996 were an average of about 0.06 meter lower than 1995 mean water-level altitudes and 0.03 meter lower than 1985--95 mean water-level altitudes. During 1996, water levels in the Yucca Mountain area could have been affected by long-term pumping at the C-hole complex that began on May 8, 1996. Through December 31, 1996, approximately 196 million liters were pumped from well UE-25 c number-sign 3 at the C-hole complex. Other ground-water pumpage in the Yucca Mountain area includes annual pumpage from water-supply wells UE-25 J-12 and UE-25 J-13 of approximately 163 and 105 million liters, respectively, and pumpage from well USW G-2 for hydraulic testing during February and April 1996 of approximately 6 million liters

223

Water levels in the Yucca Mountain area, Nevada, 1995  

International Nuclear Information System (INIS)

Water levels were monitored in 28 wells in the Yucca Mountain area, Nevada, during 1995. Seventeen wells representing 18 depth intervals were monitored periodically, generally on a monthly basis, 2 wells representing 3 depth intervals were monitored hourly, and 9 wells representing 15 depth intervals were monitored both periodically and hourly. All wells monitor water levels in Tertiary volcanic rocks except one that monitors water levels in Paleozoic carbonate rocks. Water levels were measured using calibrated steel tapes, a multiconductor cable unit, and/or pressure transducers. Mean water-level altitudes in the Tertiary volcanic rocks ranged from about 728 to about 1,034 meters above sea level during 1995. The mean water-level altitude in the well monitoring the Paleozoic carbonate rocks was about 753 meters above sea level during 1995. Mean water level altitudes were only an average of about 0.01 meters higher than 1994 mean water level altitudes. A single-well aquifer test was conducted on well UE-25 WT number-sign 12 during August and September 1995. Well USW 0-2 was also pumped during October and November 1995, in preparation for single-well aquifer test at that well. All data were acquired in accordance with a quality-assurance program to support the reliability of the data

224

Water levels in the Yucca Mountain area, Nevada, 1994  

International Nuclear Information System (INIS)

Water levels were monitored in 28 wells in the Yucca Mountain area, Nevada, during 1994. Twelve wells representing 13 intervals were monitored periodically, generally on a monthly basis, 6 wells representing 10 intervals were monitored hourly, and 10 wells representing 13 intervals were monitored both periodically and hourly. All wells monitor water levels in Tertiary volcanic rocks, except one, that monitors water levels in Paleozoic carbonate rocks. Water levels were measured using calibrated steel tapes, a multiconductor cable unit, and pressure transducers. Water-level altitudes in the Tertiary volcanic rocks ranged from about 728 to about 1,034 meters above sea level during 1994. The mean-annual water-level altitude in the well monitoring the Paleozoic carbonate rocks was about 753 meters above sea level during 1994. Water levels were only an average of about 0.01 meters lower than 1993 water levels. All data were acquired in accordance with a quality-assurance program to support the reliability of the data

225

Sensitivity of polarization fluctuations to the nature of protein-water interactions: Study of biological water in four different protein-water systems  

Science.gov (United States)

Since the time of Kirkwood, observed deviations in magnitude of the dielectric constant of aqueous protein solution from that of neat water (˜80) and slower decay of polarization have been subjects of enormous interest, controversy, and debate. Most of the common proteins have large permanent dipole moments (often more than 100 D) that can influence structure and dynamics of even distant water molecules, thereby affecting collective polarization fluctuation of the solution, which in turn can significantly alter solution's dielectric constant. Therefore, distance dependence of polarization fluctuation can provide important insight into the nature of biological water. We explore these aspects by studying aqueous solutions of four different proteins of different characteristics and varying sizes, chicken villin headpiece subdomain (HP-36), immunoglobulin binding domain protein G (GB1), hen-egg white lysozyme (LYS), and Myoglobin (MYO). We simulate fairly large systems consisting of single protein molecule and 20000-30000 water molecules (varied according to the protein size), providing a concentration in the range of ˜2-3 mM. We find that the calculated dielectric constant of the system shows a noticeable increment in all the cases compared to that of neat water. Total dipole moment auto time correlation function of water ??MW(0)?MW(t)? is found to be sensitive to the nature of the protein. Surprisingly, dipole moment of the protein and total dipole moment of the water molecules are found to be only weakly coupled. Shellwise decomposition of water molecules around protein reveals higher density of first layer compared to the succeeding ones. We also calculate heuristic effective dielectric constant of successive layers and find that the layer adjacent to protein has much lower value (˜50). However, progressive layers exhibit successive increment of dielectric constant, finally reaching a value close to that of bulk 4-5 layers away. We also calculate shellwise orientational correlation function and tetrahedral order parameter to understand the local dynamics and structural re-arrangement of water. Theoretical analysis providing simple method for calculation of shellwise local dielectric constant and implication of these findings are elaborately discussed in the present work.

Ghosh, Rikhia; Banerjee, Saikat; Hazra, Milan; Roy, Susmita; Bagchi, Biman

2014-12-01

226

Effect of fluctuating low-level chlorine concentrations on valve-movement behavior of the asiatic clam (corbicula fluminea)  

Energy Technology Data Exchange (ETDEWEB)

Asiatic clams (Corbicula fluminea) exposed to water from the upstream section of East Fork Popular Creek (Oak Ridge, TN), a stream receiving chlorine-containing industrial discharges, were monitored for changes in valve movement patterns. Individual clams were attached to an automated valve-movement monitoring apparatus and suspended in flow-through tanks located streamside. Valve-closure behavior of two clams exposed to untreated water was compared to that of two clams exposed to dechlorinated water for two 18-d periods. Chlorine concentrations in untreated water exhibited a pronounced diurnal cycle, fluctuating between a mean daily minimum of 0.02 mg/L total residual chlorine (TRC) during the day and a mean daily maximum of 0.07 mg/L TRC at night during the second monitoring period. In over 2,300 fifteen-minute intervals, clams closed for 0.70 of the intervals while exposed to untreated water, but closed for only 0.22 of the intervals while exposed to dechlorinated water. Treatment differences in valve closure were tested by repeated-measures ANOVA. A significant treatment effect on valve closure was found in the first monitoring period. Graphical analysis of valve-closure records revealed duel cycles that differed between treatments. Clams in untreated water usually opened only near midday, when TRC concentrations were lowest. Clams in dechlorinated water opened more often, for longer periods, and appeared to respond to dawn and dusk changes in light. The valve-closure behavior of clams in untreated water effectively minimized tissue exposure to waterborne TRC, presumably reducing toxic effects. Valve-closure monitoring in conjunction with other studies may help estimate the effect of tissue isolation on the toxicity or bioaccumulation of waterborne chemicals. Such estimates could improve prediction of toxicological or ecological consequences of stressful conditions on bivalves.

Ham, K.D. (Univ. of Tennessee, Knoxville, TN (United States). Graduate Program in Ecology); Peterson, M.J. (Oak Ridge National Lab., TN (United States))

1994-03-01

227

Experimental study of the fluctuations of an upward air-water flow in the circular pipe  

International Nuclear Information System (INIS)

Among all the interactions between fluids and mechanical structures, the author is in particular interested in decoupled random excitations due to a two-phase flow on a transverse mechanical structure. The aim of this work is to know the parameters of the two-phase flow which drive the excitation forces of the vibrational modes of these structures. The fluctuations of an upward bubble two-phase flow have been studied in a cylindrical pipe with and without barrier(s). Three measurements techniques have been used to determine the mean characteristics of the flow and the fluctuations of the liquid mass flux and of the liquid movement quantity (nuclear magnetic resonance), of the local void fraction (optical probe) and of the wall pressure (piezoelectric sensor). The obtained results show that the fluctuations of the mass fluxes and of the liquid movement quantities are mainly driven by the fluctuations of the surface void fractions and particularly when the mean void fraction is great. Similarly, the pressure fluctuations are strongly influenced by the surface void fraction fluctuations. In the case of a barrier context, an instability phenomenon, inducing a sudden rise of the void fraction fluctuations in the range of the mean void fraction between 5 and 20 per cent, has been observed. The presence of grids leads to the formation of strong amplitude peaks of the pressure spectra. The study on the evolution of these peaks in terms of gas and liquid velocities implies that the pressure fluctuations, caused by the phenomenon of releases of these two-phase flows, are mainly controlled by the velocity of this mixture and by the fluctuations of the surface void fraction. (author)

228

Characteristic of water level changes in river-bed during the 2012 drought in context of ground water levels in a small catchment  

Science.gov (United States)

The objective of this paper is to characterize the water level changes in river bed during the 2012 drought, in the context of ground water levels in the catchment. During the growing season , and long- lasting lack of precipitation causes atmospheric drought. Prolonged lack of precipitation causes depletion of water resources in the saturated zone . Groundwater recharge of rivers decreases , and hence streamflow droughts (summer droughts) occur, which is identified as hydrological droughts. In the phase of hydrological drought a much stronger relationship between surface and ground waters is observed. The study area is the Zago?d?onka river. The Zago?dzonka catchment is situated in the strip of the Central Polish Lowlands, in the region where droughts are the most frequent. The basin is the research area of the Department of Hydraulic Engineering of WUoLS-SGGW in Warsaw. It is one of the few catchments in Poland, with long-term records of rainfall and runoff occurrences. Hydrometeorological measurements are carried out from July 1962. The catchment area is mainly covered by one Quaternary aquifer . Quaternary layer is composed mostly of Pleistocene sands and gravels, with thickness from 4 to 40 m. Aquifer is at a depth of 1 to 12 m below ground level and is unconfined and fed by direct infiltration of precipitation. The Zago?d?onka river is the main drainage in the local hydrologic cycle. There is a strong relationship between surface waters and occurring in the Quaternary sediments. In the hydrological year 2012 hydrological and atmospheric drought occurred. The duration and deficit of streamflow drought ( defined by with the Q90 % truncation level) in 2012 was three time greater than the average value from the multi-annual period, which influenced the groundwater level fluctuations. Acknowledgment The paper has been prepared with financial support by a grant from National Science Centre

Wasilewicz, Micha?; Kaznowska, Ewa; Hejduk, Leszek

2014-05-01

229

Correlation between central corneal thickness and intraocular pressure peak and fluctuation during the water drinking test in glaucoma patients  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english OBJECTIVE: To investigate the correlation between central corneal thickness and outflow facility assessed by intraocular pressure peak and fluctuation during the water drinking test. METHODS: Fifty-five newly diagnosed primary open-angle glaucoma patients submitted to central corneal thickness measu [...] rements and water drinking test were enrolled in this retrospective study.;. Patients were divided into three groups according to their central corneal thickness. Pearson's Correlation test was performed in the groups with lower and higher pachymetric values. RESULTS: The mean age was 65,65 ± 28,28 years; 63,63% were female and 52,72% were caucasian. The mean central corneal thickness was 544,32 ± 36,86 µm, and the mean baseline intraocular pressure was 23,36 ± 6,26 mmHg. During the water drinking test, the mean intraocular pressure peak and mean intraocular pressure fluctuation were 30,43 ± 8,13 mmHg and 31,46 ± 18,46%, respectively. No relevant correlation was detected between the central corneal thickness and the intraocular pressure peak (r² = 0,021) or between the central corneal thickness and the intraocular pressure fluctuation (r² = 0,011). Group 1 presented a mean central corneal thickness of 505,81 ± 13,86 µm, and Group 3 was 583,55 ± 27,87 µm (p = 0,001). The mean intraocular pressure peak was 31,05 ± 9,05 mmHg and 27,83 ± 4,92 mmHg in Group 1 and in Group 3, respectively (p = 0,193). The difference of intraocular pressure fluctuation was not statistically significant between Group 1 (mean 28,47±16,25%) and Group3 (mean 33,27 ± 21,27%) (p = 0,43). CONCLUSION: In our case series, no correlation was found between central corneal thickness and water drinkingtest results.

Rafael Lacerda, Furlanetto; Antonio Carlos, Facio Jr; Marcelo, Hatanaka; Remo, Susanna Junior.

230

Synthesis water level control by fuzzy logic  

OpenAIRE

Purpose: This paper focuses on evolving of two types fuzzy and classical PID liquid level controller and examining whether they are better able to handle modelling uncertainties. A two stage strategy is employed to design the synthesis fuzzy and classical PID controller with the process of the first and second order and implements disorder (quadratic function).Design/methodology/approach: The synthesis of fuzzy and classical PID liquid level controller was realized with the HP laptop 6830s Co...

Berk, P.; Stajnko, D.; Vindis, P.; Mursec, B.; Lakota, M.

2011-01-01

231

Population-level mating patterns and fluctuating asymmetry in swordtail hybrids  

Science.gov (United States)

Morphological symmetry is a correlate of fitness-related traits or even a direct target of mate choice in a variety of taxa. In these taxa, when females discriminate among potential mates, increased selection on males should reduce fluctuating asymmetry (FA). Hybrid populations of the swordtails Xiphophorus birchmanni and Xiphophorus malinche vary from panmictic (unstructured) to highly structured, in which reproductive isolation is maintained among hybrids and parental species. We predicted that FA in flanking vertical bars used in sexual signalling should be lower in structured populations, where non-random mating patterns are observed. FA in vertical bars was markedly lower in structured populations than in parental and unstructured hybrid populations. There was no difference in FA between parentals and hybrids, suggesting that hybridisation does not directly affect FA. Rather, variation in FA likely results from contrasting mating patterns in unstructured and structured populations.

Culumber, Zachary W.; Rosenthal, Gil G.

2013-08-01

232

Short-time variations of the ground water level  

International Nuclear Information System (INIS)

Investigations have demonstrated that the ground water level of aquifers in the Swedish bedrock shows shorttime variations without changing their water content. The ground water level is among other things affected by regular tidal movements occuring in the ''solid'' crust of the earth variations in the atmospheric pressure strong earthquakes occuring in different parts of the world These effects proves that the system of fissures in the bedrock are not stable and that the ground water flow is influenced by both water- and airfilled fissures

233

Analysis of ground-water levels and associated trends in Yucca Flat, Nevada Test Site, Nye County, Nevada, 1951-2003  

Science.gov (United States)

Almost 4,000 water-level measurements in 216 wells in the Yucca Flat area from 1951 to 2003 were quality assured and analyzed. An interpretative database was developed that describes water-level conditions for each water level measured in Yucca Flat. Multiple attributes were assigned to each water-level measurement in the database to describe the hydrologic conditions at the time of measurement. General quality, temporal variability, regional significance, and hydrologic conditions are attributed for each water-level measurement. The database also includes narratives that discuss the water-level history of each well. Water levels in 34 wells were analyzed for variability and for statistically significant trends. An attempt was made to identify the cause of many of the water-level fluctuations or trends. Potential causes include equilibration following well construction or development, pumping in the monitoring well, withdrawals from a nearby supply well, recharge from precipitation, earthquakes, underground nuclear tests, land subsidence, barometric pressure, and Earth tides. Some of the naturally occurring fluctuations in water levels may result from variations in recharge. The magnitude of the overall water-level change for these fluctuations generally is less than 2 feet. Long-term steady-state hydrographs for most of the wells open to carbonate rock have a very similar pattern. Carbonate-rock wells without the characteristic pattern are directly west of the Yucca and Topgallant faults in the southwestern part of Yucca Flat. Long-term steady-state hydrographs from wells open to volcanic tuffs or the Eleana confining unit have a distinctly different pattern from the general water-level pattern of the carbonate-rock aquifers. Anthropogenic water-level fluctuations were caused primarily by water withdrawals and nuclear testing. Nuclear tests affected water levels in many wells. Trends in these wells are attributed to test-cavity infilling or the effects of depressurization following nuclear testing. The magnitude of the overall water-level change for wells with anthropogenic trends can be large, ranging from several feet to hundreds of feet. Vertical water-level differences at 27 sites in Yucca Flat with multiple open intervals were compared. Large vertical differences were noted in volcanic rocks and in boreholes where water levels were affected by nuclear tests. Small vertical differences were noted within the carbonate-rock and valley-fill aquifers. Vertical hydraulic gradients generally are downward in volcanic rocks and from pre-Tertiary clastic rocks toward volcanic- or carbonate-rock units.

Fenelon, Joseph M.

2005-01-01

234

Annual fluctuations of endocrine-disrupting compounds at the lower end of the Lima River, Portugal, and in adjacent coastal waters.  

Science.gov (United States)

The Lima River is a Spanish–Portuguese water body. Notwithstanding the fact that the river incorporates protected natural areas, levels of endocrine-disrupting compounds (EDCs) within its waters have never been measured; such EDCs include the following: natural and pharmaceutical oestrogens (17?-estradiol, E1, and 17?-ethynylestradiol), industrial and household pollutants (4-octylphenol, 4-nonylphenol, and their monoethoxylates and diethoxylates, and bisphenol A), phytoestrogens (formononetin, biochanin A, daidzein, genistein), and phytosterols (namely, sitosterol). To obtain an understanding of levels of EDCs, water samples were taken from eight sampling sites along the river every 2 months during a 1-year period (2011). The water samples were preconcentrated (Oasis HLB cartridges), cleaned (silica cartridges), and analysed using gas chromatography. Results showed that levels of oestrogens and industrial and household pollutants were higher in summer than in other seasons. Although oestrogens were more abundant (approximately 40 ng/L) on the southern margin of the river, levels of other pollutants were higher (approximately 124 ng/L) in the north. Phytoestrogens and sitosterol showed clear seasonal fluctuations with higher amounts of formononetin (approximately 389 ng/L), biochanin A (approximately 160 ng/L), and sitosterol (?5 µg/L) measured in summer. The overall oestrogenic load, expressed in ethynylestradiol equivalents, was 18 ng/L for oestrogens, 0.5 ng/L for industrial and household pollutants, and 13 ng/L for phytoestrogens. Water physicochemical parameters indicate anthropogenic pollution because ?nitrites,nitrates (>1 mg/L) and phosphates (approximately 0.4 mg/L) were high. The study showed that the waters of the Lima River are subject to impacts and that levels of EDCs pose risks to the river’s biota. PMID:25015732

Rocha, Maria João; Cruzeiro, Catarina; Peixoto, Cristiana; Rocha, Eduardo

2014-10-01

235

Keeping fuel covered. ABB's new water level measurement system  

International Nuclear Information System (INIS)

As one of the basic principles of reactor safety is to ensure that the fuel is covered, knowing water levels is vital. Older designs of water measurement equipment can suffer errors caused by the presence of non-condensable gases in the water during a depressurization transient. ABB Atom's new level measuring system, which uses an advanced condensation pot, is virtually independent of any variation of gas content. (UK)

236

Quality Level of Bottled Drinking Water Consumed in Saudi Arabia  

OpenAIRE

The quality of drinking water is a universal health concern and access to safe water is a fundamental human right. Many national and international organizations set certain parameters and levels for Bottled Drinking Water (BDW) to ensure their quality. The present work aims to analyze the quality of various brands of BDW used in Saudi Arabia and to compare the quality levels to the BDW standards. One hundred and twenty six samples of 54 different BDW brands were ...

Khater, Ashraf E. M.; Asma Al-Jaloud; El-taher, A.

2014-01-01

237

Prediction of subsurface water level change from satellite data  

Science.gov (United States)

This study explores the potential for predicting the spatial variation in subsurface water level change with crop growth stage from satellite data in Thabua Irrigation Project, situated in the northern central region of Thailand. The relationship between subsurface water level change from pumping water to irrigate rice in the dry season and the age of the rice was analysed. The spatial model of subsurface water level change was developed from the classification using greenness or (normalized difference vegetation index NDVI) derived from Landsat 5 Thematic Mapper data. The NDVI of 52 rice fields was employed to assess its relationship to the age of the rice. It was found that NDVI and rice age have a good correlation (R2 = 0.73). The low NDVI values (-0.059 to 0.082) in these fields were related to the young rice stage (0-30 days). NDVI and subsurface water level change were also correlated in this study and found to have a high correlation (Water level change (m day-1) = 0.3442 × NDVI - 0.0372; R2 = 0.96). From this model, the water level change caused by rice at different growth stages was derived. This was used to show the spatial variation of water level change in the project during the 1998-99 dry-season cropping. This simple method of using NDVI relationships with water level change and crop growth stages proves to be useful in determining the areas prone to excessive lowering of the subsurface water level during the dry season. This could assist in the appropriate planning of the use of subsurface water resources in dry-season cropping.

Saykawlard, Suphan; Honda, Kiyoshi; Das Gupta, Ashim; Eiumnoh, Apisit; Chen, Xiaoyong

2005-03-01

238

a Coupled Soil-Plant Approach to Modeling Convective Rainfall Initiation Induced by Water Table Fluctuation  

Science.gov (United States)

To investigate the feedback mechanisms between soil moisture dynamics and predisposition to convective rainfall, a soil-plant-atmosphere model is developed that couples the three-dimensional soil-vegetation water dynamics with an atmospheric boundary layer (ABL) slab model. The predisposition state is surrogated to the crossing of the modeled lifting condensation level and boundary layer heights. Such a predisposition is interpreted as a necessary but not sufficient condition for the initiation of convective rainfall. The model is applied to a loblolly pine plantation in the Southeastern US and used to investigate the role of vegetation on boundary layer-cloud formation. Numerical simulations highlight the feedback mechanisms occurring in the soil-plant-atmosphere continuum demonstrating that changes in the soil and plant compartments (e.g. water table drawdown, LAI decrease) impact the probability of convective rainfall occurrences.

Bonetti, S.; Manoli, G.; domec, J.; Putti, M.; Marani, M.; Katul, G. G.

2013-12-01

239

Turbulent temperature fluctuation and heat transfer to a metal surface resulting from the mixing of cold and hot water  

International Nuclear Information System (INIS)

Turbulent temperature fluctuation resulting from the mixing of cold and hot water was studied at 6.9*10/sup 6/ pascal (68 atm) around a simulated Boiling Water Reactor feedwater nozzle blend radius. The resulting heat transfer to the nozzle surface was investigated. This study shows that the instantaneous heat transfer coefficient varies from 30 percent of the steady-state value to five times the steady-state value. A discussion is given for the application of the above findings to a steady-state, two-dimensional turbulent boundary layer. The application of this information to metal surface fatigue life estimation is briefly explained. 11 refs

240

Secondary mineral evidence of large-scale water table fluctuations at Yucca Mountain, Nye County, Nevada  

International Nuclear Information System (INIS)

At Yucca Mountain, currently under consideration as a potential permanent underground repository for high-level radioactive wastes, the present-day water table is 500 to 700 m deep. This thick unsaturated zone (UZ) is part of the natural barrier system and is regarded as a positive attribute of the potential site. The USGS has studied the stable isotopes and petrography of secondary calcite and silica minerals that coat open spaces in the UZ and form irregular veins and masses in the saturated zone (SZ). This paper reviews the findings from the several studies undertaken at Yucca Mountain on its mineralogy

241

Spatio-temporal fluctuation of the chemical composition and the strontium isotopic ratios (87Sr/86Sr) of mineral waters from the Limagne d'Allier (France)  

International Nuclear Information System (INIS)

Spatial differences in levels of major and trace elements and isotopes (O, D, 87Sr/86Sr ratio) in selected mineral springs near the River Allier are presented in this Note. The investigation area is the emergence zone of mineral waters of the Limagne d'Allier, between Clermont-Ferrand and Issoire. These mineral waters contain bicarbonate, chloride and sodium. A ?2H versus ?18 diagram situates them between the local and global meteoric lines. In the emergence field of the Limagne d'Allier springs the 87Sr/86Sr ratios are remarkably uniform; only at a spring at Coudes is this ratio high. Fluctuations with time were studied at one of the unexploited boreholes at Sainte-Marguerite. Some of the elements determined varied greatly between the observed maximum and minimum. At first, the 87Sr/86Sr ratios, taken monthly, varied little, but then increased significantly for 6 months before returning to initial values. (author)

242

Study of the influence of temperature and precipitations on the levels of BTEX in natural waters.  

Science.gov (United States)

Assessment of seasonal changes in surface water quality is an important aspect for evaluating temporal variation of water due to natural or anthropogenic inputs of point and non-point sources. The objective of this paper was to investigate the influence of seasonal temperature fluctuations and precipitations on the levels of BTEX in natural waters. Principal component analysis (PCA) was used to evaluate the seasonal correlations of BTEX levels in water and to extract the parameters that are most important in assessing seasonal variations of water quality. This study was carried out as a part of VOCs monitoring program in natural water samples from Mediterranean coast. To carry out this project, a multiresidue analytical method was used. The method was based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography coupled to flame ionization detector (FID). The limits of detection LODs found for the tested analyte tested were in the 0.001-1 ?g/L range. These values were adequate for the analysis of these compounds in water samples according to the regulated values. Water samples from different points of the Mediterranean coast were analyzed during a period of three years, and were taken four times per year. Most of the compounds were below the limit established by the legislation. The results obtained by a chemometric study indicated that temperature and precipitations can be related on the BTEX levels found in water. A regression model between temperature or precipitations and BTEX concentration was obtained, thus these models can be used as predictive model for detection any non-normal concentration level. PMID:23978603

Moliner-Martínez, Y; Herraez-Hernandez, R; Verdú-Andres, J; Campíns-Falcó, P; Garrido-Palanca, C; Molins-Legua, C; Seco, A

2013-12-15

243

To calculation of the hydrostatic level indicators of total water level in the NPP steam generators  

International Nuclear Information System (INIS)

The purpose of this work consists in derivation of expressions for the actual water level in the zone of positioning level gages by the signals of the differential manometer-level gage and the steam load of the steam generator. The calculation of the hydrostatic level gages of the total water level in the NPPs steam generators with an account of the steam-water mixture density, the hydraulic resistance of the heating pipes package and immersed perforated sheet is considered. The experimental-analytical method for such calculation is proposed

244

Water level changes for Lake Turkana and climate variability during the African Humid Period  

Science.gov (United States)

The chronology of East African paleoclimate suggests the transition through the African Humid Period (AHP) at ca. 15 to 5 ka was a binary shift from wet conditions in the Late Pleistocene to current aridity. Previous studies indicate that water levels for Lake Turkana for the AHP were stable at ~88 to 98 m above current level with outflow into the White Nile Basin. This study of relict beaches around Lake Turkana indicates surprisingly >50 m variability in water level between 14 and 4 ka. The elevation of past water level is constrained by barometric and GPS-based altimetry of relict beaches and age control by 14C dating of associated mollusks and OSL dating of quartz grains from surrounding littoral and sublittoral deposits. We also include well provenanced lake level data from prior studies to constrain more fully the timing and height of water level fluctuations in the Late Quaternary. Additionally, previous studies indicate that peak water levels may be regionally amplified by increased precipitation causing overflow into the Lake Turkana Basin from the adjacent Suguta and Chew Bahir basins, particularly during high stands at ca. >8.5 ka and at 6.3 ka. Our analysis of the Lake Turkana strandplain reveals that water level may have varied by × 60 m, potentially reaching the outlet elevation at ca.11.3, 10.3, 9.0, 6.3 and 5.1 ka. There are other possible high stands at ca. 13.0, 8.4, 7.8 and 7.0 ka with limited elevational and age constraints; it is unknown if these lake stands reached the outlet elevation. Evidence from relict strand plains indicate that lake level was probably below 20 m since ca. 4.5 ka, though there were two noticeable high stands up to >12 to 18 m at ca. 830 years ago and lake levels. Inferences on the source of moisture to sustain these many high stands are based on the isotopic data on leaf wax (?Dwax) from lakes Tanganika and Victoria and associated sea surface temperature (SST) records from the Indian and the Atlantic oceans. A brief (Lake Turkana is characterized by extreme water level variability, rather than a sustained water level, with a final and rapid fall in lake level between 5.0 and 4.5 ka associated with increasing aridity.

Bloszies, C.; Forman, S. L.; Wright, D. K.

2013-12-01

245

Synthesis water level control by fuzzy logic  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: This paper focuses on evolving of two types fuzzy and classical PID liquid level controller and examining whether they are better able to handle modelling uncertainties. A two stage strategy is employed to design the synthesis fuzzy and classical PID controller with the process of the first and second order and implements disorder (quadratic function.Design/methodology/approach: The synthesis of fuzzy and classical PID liquid level controller was realized with the HP laptop 6830s Compaq NA779ES, software Matlab/Simulink 2008b, FIS (Fuzzy Inference System soft logical tool, input-output unit 500 Dragon Rider and ultrasonic sensor. Using the simulation program Matlab/Simulink/FIS we simulate the operation of fuzzy and classical controller in the liquid level regulating cycle and made a comparison between fuzzy and classical controller functioning.Findings: From the responses to step fuzzy and classical controller for first-order process shows that the actual value of the controlled variable takes the value one. Fuzzy and classical PID controller does not allow control derogation, which is also inappropriate for fuzzy and classical control cycle with incorporating disturbance. Classical PID controller in the first-order process provides short-term regulation, such as fuzzy PID controller. In fuzzy control cycle with fuzzy PID controller and incorporating disturbance in the process of second-order the control cycle is stable and at certain predetermined parameters (integral gain a control does not allow deviations.Research limitations/implications: In future research, the robustness of the fuzzy logic controller will be investigated in more details.Practical implications: Using fuzzy liquid level controller can reduce power consumption by 25%. Originality/value: Fuzzy logic controller is useful in applications of nonlinear static characteristic, where classical methods with usually classical PID controllers cannot be a satisfactory outcome

P. Berk

2011-04-01

246

Fluctuation in the Levels of Immunoglobulin M and Immunoglobulin G Antibodies for Cardiolipin and ?2-Glycoprotein among Healthy Pregnant Women  

Science.gov (United States)

Objectives: Antiphospholipid antibodies fluctuate during a healthy normal pregnancy. This study aimed to investigate the levels of both immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies for cardiolipin and ?2-glycoprotein (?2GP) among healthy pregnant women. Methods: This study was conducted between May 2010 and December 2012. A total of 75 healthy Omani pregnant women with no history of autoimmune disease were investigated during their pregnancy and 90 days after delivery at the Armed Forces Hospital in Muscat, Oman. A control group of 75 healthy Omani non-pregnant women were also investigated as a comparison. Levels of IgM and IgG antibodies for both anti-cardiolipin antibodies (ACAs) and ?2GP were measured using a standard enzyme-linked immunosorbent assay. Results: The ACA IgM levels were significantly higher in the control group compared to the pregnant women (P <0.001). No significant differences were observed in the ACA IgM levels between the control group and the pregnant women after delivery. In contrast, ACA IgG levels were significantly higher during pregnancy and after delivery compared with those of the healthy control group (P = 0.007 and 0.002, respectively). The levels of ?2GP IgG were significantly higher during pregnancy than after delivery and in the control group (P = 0.001 and <0.001, respectively). Conclusion: In this study, ACA IgG levels increased during healthy pregnancies and after normal deliveries whereas ?2GP IgG levels increased transiently during the pregnancies. Both phenomena were found to be significantly associated with a transient decline in the levels of IgM specific for these antigens. Therefore, the levels of these antibodies may be regulated during a healthy pregnancy. PMID:25364550

Al-Balushi, Mohammed S.; Hasson, Sidgi S.; Said, Elias A.; Al-Busaidi, Juma Z.; Al-Daihani, Muna S.; Othman, Mohammed S.; Sallam, Talal A.; Idris, Mohammed A.; Al-Kalbani, Moza; Woodhouse, Nicholas; Al-Jabri, Ali A.

2014-01-01

247

Water table dynamics and groundwater-surface water interaction during filling and draining of a large fluvial island due to dam-induced river stage fluctuations  

Science.gov (United States)

Dam-controlled river stage fluctuations alter groundwater-surface water interaction between persistent bars and islands and the rivers bounding them by rapidly changing hydraulic gradients and expanding hyporheic zones. A 300-m long and 80-m wide sand-gravel island with established vegetation located on the Colorado River (Austin, Texas, USA) is subjected to >1 m daily river stage variations due to upstream dam operations. Piezometer nests with probes monitored the evolution of the water table and groundwater flow paths through several cycles of dam-induced stage fluctuations. Results show that hydraulic head and the water table within the island closely track the river stage associated with dam release. Water table mounds and depressions which overlap in time were mapped through the course of one storage-release cycle over which >4,000 m3 of water moved in and out of the island. Dam operations have drastically altered groundwater-surface water connectivity between the Colorado River and the fluvial island aquifer by pumping substantial amounts of water in and out of the aquifer during dam release and storage cycles.

Francis, Blair A.; Francis, Luke K.; Cardenas, M. Bayani

2010-07-01

248

Model parameter uncertainty reduction of time series models using data-based learning algorithms for simulating groundwater level fluctuations  

Science.gov (United States)

Estimation of groundwater level (GWL) fluctuation has been an important and challenging topic in hydrology. In this study, time series models for GWL fluctuation were developed using artificial neural network (ANN) and support vector machine (SVM). This study defines 'prediction' as the estimation of GWL when the model includes past GWL measurements in input components and 'forecast' when it uses past GWL estimated values. In order to reduce model parameter uncertainty for GWL forecast, the classic model building process was modified introducing weighting factors to the objective function. The developed models were applied to rainfall and GWL time series data of 5 groundwater monitoring stations in National Groundwater Monitoring Network (NGMN) of Korea: HC, MH, YH, PC and CS station, in order to compare the models' performance for prediction and forecast of GWL fluctuation and evaluate the impact of the weighting factors on model stability. Results showed that root mean squared error (RMSE) values ranged from 0.05 m to 0.11 m for the GWL prediction and 0.072 m to 0.159 m for the GWL forecast. Correlation coefficient values were over 0.91 and 0.87 for the prediction and forecast, respectively. The ANN model was more frequently selected than SVM for the prediction, whereas vice versa for the forecast. In the present study, FC-TS value was defined as RMSE values in the forecast to testing stage for examining the model parameter uncertainty. The FC-TS values decreased significantly when the weighting factors were utilized, which implies that use of the weighting factors reduced the uncertainty of the developed time series models.

Yoon, H.; Hyun, Y.; Lee, K.; Ha, K.; Ko, K.

2012-12-01

249

Impact of groundwater levels on evaporation and water-vapor fluxes in highly saline soils  

Science.gov (United States)

In aquifers of arid and hyper-arid zones, such as those occurring in the Chilean Andes high plateau, it is important to determine both the quantity and location of water discharges at the temporal scales of interest to close the basin's water budget and thus, to manage the water resource properly. In zones where shallow aquifers are the main source of water, overexploitation of the water resource changes the dynamics of water, heat and solute transport in the vadose zone. As aquifers are exploited, fluctuations in depth to groundwater are exacerbated. These fluctuations modify both soil structure and evaporation from the ground, which is typically the most important discharge from the water budget and is very difficult to estimate. Therefore, a correct quantification of evaporation from these soils is essential to improve the accuracy of the water balance estimation. The objective of this study was to investigate the evaporation processes and water-vapor fluxes in a soil column filled with a saline soil from the Salar del Huasco basin, Chile. Water content, electrical conductivity and temperature at different depths in the soil profile were monitored to determine the liquid and vapor fluxes within the soil column. The results showed that evaporation is negligible when the groundwater table is deeper than 1 m. For shallower groundwater levels, evaporation increases in an exponential fashion reaching a value of 3 mm/day when the groundwater table is near the surface of the ground. These evaporation rates are on the same order of magnitude than the field measurements, but slightly lower due to the controlled conditions maintained in the laboratory. Isothermal fluid fluxes were predominant over the non-isothermal fluid and water vapor fluxes. The net flux for all the phreatic levels tested in the laboratory showed different behaviors, with ascending or descending flows as a consequence of changes in water content and temperature distribution within the soil. It was found that evaporation from bare soils occurs as a consequence of vapor transport due to the thermal gradients. This vapor transport was also influences by the salinity of the soil.

Munoz, J. F.; Hernández, M. F.; Braud, I.; Gironas, J. A.; Suarez, F. I.

2012-12-01

250

Water level-dependent morphological plasticity in Sagittaria montevidensis Cham. and Schl. (Alismataceae).  

Science.gov (United States)

Aquatic plants are able to alter their morphology in response to environmental condition variation, such as water level fluctuations. The aim of this study was to evaluate the effect of water level on Sagittaria montevidensis morphology through measures of vegetative structures formed in drought and flood periods. We hypothesised that the plant height and the biomass of S. montevidensis leaves will increase during flood periods, while the biomass and diameter of petioles, and the basal plant area will increase during dry periods. We sampled a total amount of 270 individuals in nine sediment banks per visit, totalling 1080 plants. In order to compare plant morphology between dry and flood periods, we measured the water level in each bank and took the following variables for each plant: diameter, height and diameter of the biggest petiole. In order to compare biomass allocation between dry and flood periods, we sampled a total amount of 90 individuals in nine sediment banks per visit, totalling 360 plants. Plants were dried and weighed in the laboratory. All measured morphologic traits, as well as the biomass of leaf blades and petioles, were higher during flood periods, indicating that water level highly influences the morphology of S. montevidensis individuals. Our results suggest that these morphological responses allow survival and maintenance of S. montevidensis populations under environmental stress. These results can be linked to the invasive potential of S. montevidensis and sheds light on basic management practices that may be applied in the future. PMID:25627386

Demetrio, G R; Barbosa, M E A; Coelho, F F

2014-08-01

251

Fluctuation of TeV to EeV Energy Muons and Induced Muon Showers in Water  

CERN Document Server

By using the integral method in the muon propagation through water, we calculate the range fluctuation of high and ultra high energy muons. Many authors divide all radiative processes into two parts, namely, the continuous part and radiative part in their Monte Carlo simulation in order to consider the fluctuation in the both ranges and energies of the muons, while we treat all stochastic processes as exactly as possible, without the introduction of the continuous parts in all stochastic processes. The validity of our Monte Carlo method is checked by the corresponding analytical method which is methodologically independent on the Monte Carlo procedure. Accompanied cascade showers are generated by the direct electron pair production, bremsstrahlung and photo-nuclear interaction. These showers are calculated by the exact Monte Carlo Method in one dimensional way. We report survival probabilities, range distributions and examples of individual muon behavior.

Okumura, Y; Misaki, A

2010-01-01

252

Small-angle X-ray scattering study on the fluctuations of supercritical aqueous solution of n-pentane along the critical isotherm of water  

Science.gov (United States)

Fluctuation terms of the supercritical aqueous solutions of n-pentane, i.e., those of densities, concentrations, and their correlation terms, were evaluated by small-angle X-ray scattering intensity in combination with isothermal compressibility and partial molar volumes. The fluctuations increased significantly with the fluid density up to the region of middle density, ˜0.2 g cm-3, and then decreased at higher density. In the region where the fluctuations took maxima or minima, the density was lower than those of water critical density. The particle-number fluctuations of individual components obtained from the fluctuation terms show that water molecules are distributed more inhomogeneously than n-pentane, especially in the region of ˜0.3 g cm-3.

Morita, Takeshi; Murai, Hiromi; Kase, Syunsuke; Nishikawa, Keiko

2012-08-01

253

A multi-source satellite data approach for modelling Lake Turkana water level: calibration and validation using satellite altimetry data  

Science.gov (United States)

Lake Turkana is one of the largest desert lakes in the world and is characterized by high degrees of inter- and intra-annual fluctuations. The hydrology and water balance of this lake have not been well understood due to its remote location and unavailability of reliable ground truth datasets. Managing surface water resources is a great challenge in areas where in-situ data are either limited or unavailable. In this study, multi-source satellite-driven data such as satellite-based rainfall estimates, modelled runoff, evapotranspiration, and a digital elevation dataset were used to model Lake Turkana water levels from 1998 to 2009. Due to the unavailability of reliable lake level data, an approach is presented to calibrate and validate the water balance model of Lake Turkana using a composite lake level product of TOPEX/Poseidon, Jason-1, and ENVISAT satellite altimetry data. Model validation results showed that the satellite-driven water balance model can satisfactorily capture the patterns and seasonal variations of the Lake Turkana water level fluctuations with a Pearson's correlation coefficient of 0.90 and a Nash-Sutcliffe Coefficient of Efficiency (NSCE) of 0.80 during the validation period (2004-2009). Model error estimates were within 10% of the natural variability of the lake. Our analysis indicated that fluctuations in Lake Turkana water levels are mainly driven by lake inflows and over-the-lake evaporation. Over-the-lake rainfall contributes only up to 30% of lake evaporative demand. During the modelling time period, Lake Turkana showed seasonal variations of 1-2 m. The lake level fluctuated in the range up to 4 m between the years 1998-2009. This study demonstrated the usefulness of satellite altimetry data to calibrate and validate the satellite-driven hydrological model for Lake Turkana without using any in-situ data. Furthermore, for Lake Turkana, we identified and outlined opportunities and challenges of using a calibrated satellite-driven water balance model for (i) quantitative assessment of the impact of basin developmental activities on lake levels and for (ii) forecasting lake level changes and their impact on fisheries. From this study, we suggest that globally available satellite altimetry data provide a unique opportunity for calibration and validation of hydrologic models in ungauged basins.

Velpuri, N. M.; Senay, G. B.; Asante, K. O.

2012-01-01

254

A multi-source satellite data approach for modelling Lake Turkana water level: calibration and validation using satellite altimetry data  

Directory of Open Access Journals (Sweden)

Full Text Available Lake Turkana is one of the largest desert lakes in the world and is characterized by high degrees of inter- and intra-annual fluctuations. The hydrology and water balance of this lake have not been well understood due to its remote location and unavailability of reliable ground truth datasets. Managing surface water resources is a great challenge in areas where in-situ data are either limited or unavailable. In this study, multi-source satellite-driven data such as satellite-based rainfall estimates, modelled runoff, evapotranspiration, and a digital elevation dataset were used to model Lake Turkana water levels from 1998 to 2009. Due to the unavailability of reliable lake level data, an approach is presented to calibrate and validate the water balance model of Lake Turkana using a composite lake level product of TOPEX/Poseidon, Jason-1, and ENVISAT satellite altimetry data. Model validation results showed that the satellite-driven water balance model can satisfactorily capture the patterns and seasonal variations of the Lake Turkana water level fluctuations with a Pearson's correlation coefficient of 0.90 and a Nash-Sutcliffe Coefficient of Efficiency (NSCE of 0.80 during the validation period (2004–2009. Model error estimates were within 10% of the natural variability of the lake. Our analysis indicated that fluctuations in Lake Turkana water levels are mainly driven by lake inflows and over-the-lake evaporation. Over-the-lake rainfall contributes only up to 30% of lake evaporative demand. During the modelling time period, Lake Turkana showed seasonal variations of 1–2 m. The lake level fluctuated in the range up to 4 m between the years 1998–2009. This study demonstrated the usefulness of satellite altimetry data to calibrate and validate the satellite-driven hydrological model for Lake Turkana without using any in-situ data. Furthermore, for Lake Turkana, we identified and outlined opportunities and challenges of using a calibrated satellite-driven water balance model for (i quantitative assessment of the impact of basin developmental activities on lake levels and for (ii forecasting lake level changes and their impact on fisheries. From this study, we suggest that globally available satellite altimetry data provide a unique opportunity for calibration and validation of hydrologic models in ungauged basins.

N. M. Velpuri

2012-01-01

255

Quantitative assessment of glacial fluctuations in the level of Lake Lisan, Dead Sea rift  

Science.gov (United States)

A quantitative understanding of climatic variations in the Levant during the last glacial cycle is needed to support archaeologists in assessing the drivers behind hominin migrations and cultural developments in this key region at the intersection between Africa and Europe. It will also foster a better understanding of the region's natural variability as context to projections of modern climate change. Detailed documentation of variations in the level of Lake Lisan - the lake that occupied the Dead Sea rift during the last glacial cycle - provides crucial climatic information for this region. Existing reconstructions suggest that Lake Lisan highstands during cold intervals of the last glacial cycle represent relatively humid conditions in the region, but these interpretations have remained predominantly qualitative. Here, I evaluate realistic ranges of the key climatological parameters that controlled lake level, based on the observed timing and amplitudes of lake-level variability. I infer that a mean precipitation rate over the wider catchment area of about 500 mm y-1, as proposed in the literature, would be consistent with observed lake levels if there was a concomitant 15-50% increase in wind speed during cold glacial stadials. This lends quantitative support to previous inferences of a notable increase in the intensity of Mediterranean (winter) storms during glacial periods, which tracked eastward into the Levant. In contrast to highstands during ‘regular’ stadials, lake level dropped during Heinrich Events. I demonstrate that this likely indicates a further intensification of the winds during those times.

Rohling, Eelco J.

2013-06-01

256

Potential effects of climate change on the water level, flora and macro-fauna of a large neotropical wetland.  

Science.gov (United States)

Possible consequences of climate change in one of the world's largest wetlands (Ibera, Argentina) were analysed using a multi-scale approach. Climate projections coupled to hydrological models were used to analyse variability in wetland water level throughout the current century. Two potential scenarios of greenhouse gas emissions were explored, both resulting in an increase in the inter-annual fluctuations of the water level. In the scenario with higher emissions, projections also showed a long-term negative trend in water-level. To explore the possible response of biota to such water-level changes, species-area relationships of flora and aerial censuses of macro-fauna were analysed during an extraordinary dry period. Plant species richness at the basin scale was found to be highly resistant to hydrological changes, as the large dimension of the wetland acts to buffer against the water-level variations. However, local diversity decreased significantly with low water levels, leading to the loss of ecosystem resilience to additional stressors. The analysis of macro-fauna populations suggested that wetland provides refuge, in low water periods, for the animals with high dispersal ability (aquatic and migratory birds). On the contrary, the abundance of animals with low dispersal ability (mainly herbivorous species) was negatively impacted in low water periods, probably because they are required to search for alternative resources beyond the wetland borders. This period of resource scarcity was also related to increased mortality of large mammals (e.g. marsh deer) around water bodies with high anthropogenic enrichment and cyanobacteria dominance. The synergy between recurrent climatic fluctuations and additional stressors (i.e. biological invasions, eutrophication) presents an important challenge to the conservation of neotropical wetlands in the coming decades. PMID:23874446

Úbeda, Bárbara; Di Giacomo, Adrian S; Neiff, Juan José; Loiselle, Steven A; Poi, Alicia S Guadalupe; Gálvez, José Ángel; Casco, Silvina; Cózar, Andrés

2013-01-01

257

Water level monitoring and controlling system in reactor pressure vessel  

International Nuclear Information System (INIS)

Upon controlling of a water level conducted before an operation of removing a head of a reactor pressure vessel performed upon periodical inspection of a power plant, a supersonic displacement sensor capable of conducting measurement on the basis of cm unit is used as a water level indicator. The water level in the reactor pressure vessel can be controlled to a position above a steam dryer accurately by a remote operation while measuring the water level in the pressure vessel at a high accuracy. In addition, a dose equivalent gauge for evaluating the dose equivalent rate of the operation circumstance is previously disposed before the removal of the head of the reactor pressure vessel to reduce the amount of operation and exposure dose of a radiation operation manager. These supersonic displacement sensor and dose equivalent gauge are made detachable so that they can be disposed only when they are required thereby enabling to minimize the deterioration of the device. (N.H.)

258

Trace-level mercury removal from surface water  

International Nuclear Information System (INIS)

Many sorbents have been developed for the removal of mercury and heavy metals from waters; however, most of the data published thus far do not address the removal of mercury to the target levels represented in this project. The application to which these sorbents are targeted for use is the removal of mercury from microgram-per-liter levels to low nanogram-per-liter levels. Sorbents with thiouronium, thiol, amine, sulfur, and proprietary functional groups were selected for these studies. Mercury was successfully removed from surface water via adsorption onto Ionac SR-4 and Mersorb resins to levels below the target goal of 12 ng/L in batch studies. A thiol-based resin performed the best, indicating that over 200,000 volumes of water could be treated with one volume of resin. The cost of the resin is approximately $0.24 per 1,000 gal of water

259

Water-level variations in the northern levantine sea  

OpenAIRE

Characteristics of water level variations in the northern Levantine Sea have been investigated by reference to a sequence of hourly water level observations at Antalya and Iskenderun. Long and short period oscillations of non-tidal origin have been identified. Long-period oscillations (several days) correspond to variations in barometric pressure; the short-period oscillations (2.8 to 4.6 hours) can be attributed to seiche-like motions. The tidal oscillations are small in amplitude, with a sp...

Yuce, H.; Alpar, B.

1994-01-01

260

Monitoring Water Level in Agriculture Using Sensor Networks  

OpenAIRE

Recent advances in communications technology andwireless sensor networks made new trends to emerge inagriculture sector. One such new trend is Precision Agriculture.In this paper we are giving brief outline of using Wireless SensorNetworks (WSN) in Monitoring water level in the farm area forPrecision Agriculture. This algorithm offers a maximumopportunity of delivery of water level informationpackets/signals to base station as it also computes a threshold aswell as does calculates values base...

Iqbal Singh; Meenakshi Bansal

2011-01-01

261

Geomorphological evidence of water level changes in Nepenthes Mensae, Mars  

Science.gov (United States)

In the western sector of Nepenthes Mensae, Mars, there are some geomorphological features that could be related to a standing water sheet in the area, such as fluvial terraces, deltas and shorelines. A detailed analysis of these features reveals two variations in water level, probably related to tectonic processes, as suggested by the existence of a fissural volcano at this site.

de Pablo, Miguel Ángel; Pacifici, Andrea

2008-08-01

262

Ground-water levels in Arkansas, spring 1985  

Science.gov (United States)

The report contains 622 ground-water level measurements made in observation wells in Arkansas in the spring of 1985. In addition , the report contains well hydrographs relating to the Quaternary aquifer and the Sparta Sand aquifers, the most important aquifers with respect to ground-water availability and use in Arkansas. (USGS)

Edds, Joe; Spencer, J.L.

1985-01-01

263

Current-induced two-level fluctuations in pseudo spin-valves (Co/Cu/Co) nanostructures  

CERN Document Server

Two-level fluctuations of the magnetization state of pseudo spin-valve pillars Co(10 nm)/Cu(10 nm)/Co(30 nm) embedded in electrodeposited nanowires (~40 nm in diameter, 6000 nm in length) are triggered by spin-polarized currents of 10^7 A/cm^2 at room temperature. The statistical properties of the relaxation times between transitions from parallel to antiparallel magnetization states (and vice versa) reveal two effects with qualitatively different dependences on current intensity. The current appears to have the effect of a bias field, evaluated experimentally as the counteracting applied field that equalizes the mean relaxation times. When the energy profile is a symmetric double well, the effect of a current density of 10^7 A/cm^2 is to decrease the effective energy barrier by 1000 K. The bias field changes sign when the current polarity is reversed. The barrier is lowered, irrespective of the sign of the current.

Fabian, A C; Guisan, S S; Hoffer, X; Dubey, M; Gravier, L; Ansermet, J P; Wegrowe, J E

2003-01-01

264

Sea-level fluctuations and coastal evolution in the state of Rio de Janeiro, southeastern Brazil  

Scientific Electronic Library Online (English)

Full Text Available O presente trabalho tem como objetivo investigar as variações do nível relativo do mar e a evolução costeira durante o Holoceno no litoral do Estado do Rio de Janeiro, com base em indicadores geológicos e biológicos. Realizou-se levantamento altimétrico, execução de sondagens e datações ao 14C na pl [...] anície costeira e em afloramentos de rochas de praia. A partir dos dados obtidos, construiu-se uma curva do nível relativo do mar para o Holoceno. Pela primeira vez na costa brasileira foi identificado um recorde negativo do nível relativo do mar, envolvendo a transição final do Pleistoceno e início do Holoceno. Após a transição, iniciou-se um processo relativamente rápido de subida do nível do mar. Há aproximadamente 8.500 anos cal A.P., o nível marinho, encontrava-se a - 0.5 m abaixo do nível atual. O “zero” (nível médio atual) foi ultrapassado pela primeira vez no Holoceno há cerca de 7.500 anos A.P. Entre 5.500 - 4.500 cal anos A.P, o nível relativo do mar atingiu o primeiro máximo holocênico com altura máxima de +2.50 m acima do atual. A descida do nível relativo do mar subseqüente ao máximo transgressivo, levou à construção de terraços marinhos, resultando na progradação da linha de costa até o presente. A maioria dos resultados corroboram dados já obtidos em outros segmentos da costa atlântica da América do Sul. Resultados aqui apresentados são consistentes com pesquisas anteriores e ajudam refinar o registro do nível relativo do mar Holoceno na costa brasileira. Abstract in english The present paper aims to investigate the relative sea-level and the coastal evolution during the Holocene in the Rio de Janeiro coastline, based on geological and biological indicators. Using topographic survey, excavation and coring, and 14C dating of these coastal deposits and beachrocks outcrops [...] , we have reconstructed a sea-level curve for the Holocene. For the first time on the Brazilian coast it was identified a negative record of relative sea-level during Late Pleistocene and Early Holocene transition. After the transition, a relatively rapid increase of sea-level began. At approximately at 8500 cal yr BP, the sea-level was 0.5 m below the current level, was overtaken for the first time in the Holocene, at approximately 7500 cal yr BP. The maximum level of +2.5 m was reached between 4770 and 4490 cal yr BP. At the point of maximum transgression, the sea-level began a general behavior of lowering until the present. These results confirm other data already obtained elsewhere along the Atlantic coast of South America. The results of this study are consistent with previous researches and they help to refine the Holocene sea-level record along the Brazilian coast.

JOÃO WAGNER A., CASTRO; KENITIRO, SUGUIO; JOSÉ C.S., SEOANE; ALINE M. DA, CUNHA; FABIO F., DIAS.

2014-06-01

265

Performance of broilers submitted to high CO2 levels during incubation combined with temperature fluctuations at late post-hatch  

Scientific Electronic Library Online (English)

Full Text Available Incubation represents around 1/3 of the life cycle of broilers of modern strains; therefore, the appropriate management of this period is crucial to ensure the quality of the neonate. An experiment evaluated the effect of carbon dioxide concentrations during incubation on the live performance, heart [...] morphology, and differential leukocyte count in the blood of broilers submitted to fluctuating temperatures between 35 and 42 days of age. In total, 2,520 fertile eggs were distributed according to a completely randomized design with four CO2 concentrations (4,000; 6,000; 8,000 and 10,000 ppm) during the first ten days of incubation, after which all eggs were incubated at the same CO2 level (4,000 ppm). After hatching, male chicks were placed in the experimental broiler houses, and at 35 days of age, 25 birds from each level of CO2 were separated and placed in cages to study the effect of cyclic temperature variations up to 42 days of age on their live performance, heterophil:lymphocyte ratio, and heart morphology. At 42 days of age, blood was collected for hematology and two birds per replicate were sacrificed and evaluated for ascites score and heart and liver relative weights. Heart morphology was assessed by analyzing digital images. In this experiment, hypercapnia during incubation and fluctuating temperatures during the growout did not affect mortality, ascites score, heart and liver relative weights, or heart characteristics (p>0.05). However, heterophill:lymphocyte ratio increased (p

JIM, Fernandes; C, Bortoluzzi; AFG, Esser; JP, Contini; PB, Stokler; D, Faust.

2014-09-01

266

Contribution of climate-driven change in continental water storage to recent sea-level rise  

Science.gov (United States)

Using a global model of continental water balance, forced by interannual variations in precipitation and near-surface atmospheric temperature for the period 1981-1998, we estimate the sea-level changes associated with climate-driven changes in storage of water as snowpack, soil water, and ground water; storage in ice sheets and large lakes is not considered. The 1981-1998 trend is estimated to be 0.12 mm/yr, and substantial interannual fluctuations are inferred; for 1993-1998, the trend is 0.25 mm/yr. At the decadal time scale, the terrestrial contribution to eustatic (i.e., induced by mass exchange) sea-level rise is significantly smaller than the estimated steric (i.e., induced by density changes) trend for the same period, but is not negligibly small. In the model the sea-level rise is driven mainly by a downtrend in continental precipitation during the study period, which we believe was generated by natural variability in the climate system.

Milly, P.C.D.; Cazenave, A.; Gennero, M.C.

2003-01-01

267

Groundwater Evapotranspiration from Diurnal Water Table Fluctuation: a Modified White Based Method Using Drainable and Fillable Porosity  

Science.gov (United States)

In shallow unconfined aquifers, the water table usually shows a distinct diurnal fluctuation pattern corresponding to the twenty-four hour solar radiation cycle. This diurnal water table fluctuation (DWTF) signal can be used to estimate the groundwater evapotranspiration (ETg) by vegetation, a method known as the White [1932] method. Water table fluctuations in shallow phreatic aquifers is controlled by two distinct storage parameters, drainable porosity (or specific yield) and the fillable porosity. Yet, it is implicitly assumed in most studies that these two parameters are equal, unless hysteresis effect is considered. The White based method available in the literature is also based on a single drainable porosity parameter to estimate the ETg. In this study, we present a modification of the White based method to estimate ETg from DWTF using separate drainable (?d) and fillable porosity (?f) parameters. Separate analytical expressions based on successive steady state moisture profiles are used to estimate ?d and ?f, instead of the commonly employed hydrostatic moisture profile approach. The modified method is then applied to estimate ETg using the DWTF data observed in a field in northeast Florida and the results are compared with ET estimations from the standard Penman-Monteith equation. It is found that the modified method resulted in significantly better estimates of ETg than the previously available method that used only a single, hydrostatic-moisture-profile based ?d. Furthermore, the modified method is also used to estimate ETg even during rainfall events which produced significantly better estimates of ETg as compared to the single ?d parameter method.

Acharya, S.; Mylavarapu, R.; Jawitz, J. W.

2012-12-01

268

Rate of bentazone transformation in four layers of a humic sandy soil profile with fluctuating water table  

OpenAIRE

The rate of transformation of a pesticide as a function of the depth in the soil is needed as an input into computations on the risk of residues leaching to groundwater. The herbicide bentazone was incubated at 15 °C in soil materials derived from four layers at depths of up to 2.5 m in a humic sandy soil profile with a fluctuating water table (0.8 to 1.4 m), while simulating the redox conditions existing in the field. Gamma-irradiation experiments indicated that bentazone is mainly transfor...

Leistra, M.; Smelt, J. H.; Matser, A. M.; Bogte, J. J.; Pas, L. J. T.

2001-01-01

269

Does the accuracy of fine-scale water level measurements by vented pressure transducers permit for diurnal evapotranspiration estimation?  

Science.gov (United States)

Evapotranspiration (ET) estimation methods based on diurnal water level (surface or groundwater) fluctuations are sensitive to measurement accuracy (McLaughlin and Cohen, 2011; Cuevas et al., 2010). Water level fluctuations are often measured by pressure transducers of varying design and precision. Available total pressure transducers require a compensation for barometric pressure change supplied by barometric pressure transducers. Recently McLaughlin and Cohen (2011) as well as Cuevas et al. (2010) analyzed the 'thermal artifacts' of such transducer-pair data questioning the applicability of sub-daily water level measurements in non-buffered thermal mode for diurnal ET estimation. Similar problems should not, in principle, occur for so-called vented pressure transducers. With the help of ancillary manual measurements, this study verifies the accuracy of vented pressure transducer obtained ultra-fine scale (temporal resolution of 1-10 min) stream- and groundwater level data. Thermal effects were examined by a statistical analysis of concurrent water level and temperature data. The results support the thermal artifact-free nature of vented pressure transducers and therefore their suitability for diurnal ET estimation purposes when proper maintenance and periodic calibrations are provided. In the lack of such measures, diurnal temperature changes can induce errors in vented pressure transducer readings as well.

Gribovszki, Zoltán; Kalicz, Péter; Szilágyi, József

2013-04-01

270

Water level regime in the Danube river and its river branches  

International Nuclear Information System (INIS)

In the major part of the left side river branch system, fed through the intake structure at Dobrohost, relatively high level conditions are kept during the whole vegetation period. The flow in the upstream part (upstream line D) is comparable with the pre-dam stages for 4000 m3 s-1 in Bratislava and between lines E to D with the pre dam 3000 m3 s-1. The very downstream part of the system is controlled by the water level fluctuation in the Danube. The water level in the old Danube could be increased substantially by constructing a series of submerged hydraulic structures. An increase in water level of more than 1.5 m was achieved by the discharge of 400 m3 s-1 in the old Danube using preliminary design of structures situated in the reach between rkm 1817-1825. The guaranteed width of 90 m and depth of 2 m in the old Danube could be achieved at discharge rates of 1500 m3 s-1 or higher. The flow velocity is about 0.5 m s-1 or higher. The flow velocity is about 0.5 m s-1 in the reaches between the structures at discharge 400 m3 s-1 and about 1 m s-1 at discharge of m3 s-1. (authors). 8 figs., 1 map, 12 refs

271

Behavior of beaver in lakes with varying water levels in Northern Minnesota  

Science.gov (United States)

We studied the effects of winter water drawdowns (2.3 m) on beavers in Voyageurs National Park, Minnesota, USA. Our study was designed to sample areas within the park that differed in water drawdown regime. Lodges were counted and beavers were livetrapped and radio-implanted to study behavior, movements, and mortality. Active beaver lodge density, determined by aerial survey in 1984 and 1986, was greatest along the shoreline of the drawdown reservoir. In winter beavers living on the drawdown reservoir spent less time inside their lodges than did beavers from stable water environments, foraged more above ice, and they were unable to fully use stored food. Only one case of starvation in the drawdown reservoir was documented, but beavers in reservoirs that were drawn down survived winter in poorer condition than did beavers living in areas in which water levels remained high. In spite of an increasing population and lack of widespread mortality, winter water drawdowns did alter beaver behavior. To reduce these impacts, total annual water fluctuation should not exceed 1.5 m, and winter drawdown should not exceed 0.7 m. Possible management alternatives and costs are discussed.

Smith, Douglas W.; Peterson, Rolf O.

1991-05-01

272

WATER-LEVEL MONITOR FOR BOREWELL AND WATER TANK BASED ON GSM  

Directory of Open Access Journals (Sweden)

Full Text Available Now a days, home automation & remote control and monitoring systems have seen a rapid growth in terms of technology. Apparently there is no early warning system to monitor the tank water level and bore well water level when it has reached the critical level. In this paper we have provided water level monitoring in the tank as well as in the bore well. If the water level in a bore well drops below the threshold level for pumping its pump motor may get air locked or more burn out due to dry running. It is awkward for farmers to walk all the way to their fields at night just to switch the pump motor off. Besides, he may never get to identify the problem. This problem can be solved by using this GSM based system that will automatically make a call to the user mobile phone, when the water Level in the bore well drops threshold below or rises to the threshold level for pumping. The user can also remotely switch on or off the pump motor by sending a SMS from his mobile phone. The system is simple, reliable, portable and affordable. We proposed the work in which, Whenever water level in the tankdrops below the required level the system try to fill the tank by switching on the bore well motor to pump the water into the tank It is must to have enough water in the bore well to avoid the formation of air gap or empty running of bore well motor. High precision water level sensor is used to identify the reference water level to activate and deactivate the motor and system properly by interfacing the sensor devices into the well definedembedded system.

R.Ramani

2012-10-01

273

Dynamics of a Landau-Zener non-dissipative system with fluctuating energy levels  

Science.gov (United States)

This paper considers a Landau-Zener (two-level) system influenced by a three-dimensional Gaussian and non-Gaussian coloured noise and finds a general form of the time dependent diabatic quantum bit (qubit) flip transition probabilities in the fast, intermediate and slow noise limits. The qubit flip probability is observed to mimic (for low-frequencies noise) that of the standard LZ problem. The qubit flip probability is also observed to be the measure of quantum coherence of states. The transition probability is observed to be tailored by non-Gaussian low-frequency noise and otherwise by Gaussian low-frequency coloured noise. Intermediate and fast noise limits are observed to alter the memory of the system in time and found to improve and control quantum information processing.

Fai, L. C.; Diffo, J. T.; Ateuafack, M. E.; Tchoffo, M.; Fouokeng, G. C.

2014-12-01

274

Fluctuations in indoor radon levels in dwellings in a volcanic area of a temperate tropical region  

International Nuclear Information System (INIS)

Mexico City is located in the central section of the Neo-Volcanic Mexican Belt at an altitude of 2240 m. Air pollution is currently a huge environmental problem in the city. With the aim of determining any anomalous behavior patterns in relation to indoor radon, which could possibly have had an effect on patients with lung diseases who are smokers, a study was performed in indoor atmospheres over a period of several months. Radon was measured using both passive and continuous radon monitoring devices. The results of our investigations indicate that the dwellings of patients with lung diseases show no special characteristics as compared to homes included in a control group. However, in both cases, an enhancement in the indoor radon concentration levels during the night and early morning periods was observed, the periods in which most people are at home resting. (orig.)

275

Environmental factors related to water level regulation - a comparative study in northern Finland  

International Nuclear Information System (INIS)

The environmental conditions of the littoral zone were studied in the regulated Lake Ontojaervi and the unregulated Lake Lentua in northern Finland. The general aims of the study were to analyse the environmental factors related to water level regulation in the littoral zone and to produce information for assessing the effects of hydroelectric development in northern lakes. The study was basically carried out by comparing the littoral environments of the two study lakes. The most visible effects of water level regulation were related to the raised water level, which yielded erosion of sandy shores at the beginning of the regulation. Another effect of lake regulation was the altered fluctuation of the water level, which led to bottom instability and increased the size of the frozen and ice penetration zones. The effect of ice penetration was also easy to recognize on the shores of Lake Ontojaervi, where the surface sediment was frozen to a greater depth and across wider areas than in Lake Lentua. Below the freezing zone, the ice just pressed down on the sediment. The shores of Lake Ontojaervi were steeper than those of Lake Lentua, which affected the distribution of bottom types, with sandy bottoms being more common in Lake Lentua than in Lake Ontojaervi. The factors related to site exposure included effective fetch and the shape of the shoreline. The sedimentation level correlated only with the slope and was not predicted by the fetch or shape. The vertical reduction he fetch or shape. The vertical reduction of light was estimated on the basis of water colour. The main environmental factors from the two lakes were used in a discriminant analysis to predict the bottom type distribution of the littoral (r2 = 0.41). (orig.) 66 refs

276

Predicting Atrazine Levels in Water Utility Intake Water for MCL Compliance  

Science.gov (United States)

To protect human health, atrazine concentrations in drinking water must not exceed its maximum contaminant level (MCL) of 3 ug/L. The United States Environmental Protection Agency (USEPA) mandates that municipal water providers sample quarterly to determine MCL compliance. Atrazine levels were mon...

277

Ground-water discharge determined from measurements of evapotranspiration, other available hydrologic components, and shallow water-level changes, Oasis Valley, Nye County, Nevada  

International Nuclear Information System (INIS)

Oasis Valley is an area of natural ground-water discharge within the Death Valley regional ground-water flow system of southern Nevada and adjacent California. Ground water discharging at Oasis Valley is replenished from inflow derived from an extensive recharge area that includes the northwestern part of the Nevada Test Site (NTS). Because nuclear testing has introduced radionuclides into the subsurface of the NTS, the U.S. Department of Energy currently is investigating the potential transport of these radionuclides by ground water flow. To better evaluate any potential risk associated with these test-generated contaminants, a number of studies were undertaken to accurately quantify discharge from areas downgradient in the regional ground-water flow system from the NTS. This report refines the estimate of ground-water discharge from Oasis Valley. Ground-water discharge from Oasis Valley was estimated by quantifying evapotranspiration (ET), estimating subsurface outflow, and compiling ground-water withdrawal data. ET was quantified by identifying areas of ongoing ground-water ET, delineating areas of ET defined on the basis of similarities in vegetation and soil-moisture conditions and computing ET rates for each of the delineated areas. A classification technique using spectral-reflectance characteristics determined from satellite imagery acquired in 1992 identified eight unique areas of ground-water ET. These areas encompass about 3,426 acres of sparsely to denselys about 3,426 acres of sparsely to densely vegetated grassland, shrubland, wetland, and open water. Annual ET rates in Oasis Valley were computed with energy-budget methods using micrometeorological data collected at five sites. ET rates range from 0.6 foot per year in a sparse, dry saltgrass environment to 3.1 feet per year in dense meadow vegetation. Mean annual ET from Oasis Valley is estimated to be about 7,800 acre-feet. Mean annual ground-water discharge by ET from Oasis Valley, determined by removing the annual local precipitation component of 0.5 foot, is estimated to be about 6,000 acre-feet. Annual subsurface outflow from Oasis Valley into the Amargosa Desert is estimated to be between 30 and 130 acre-feet. Estimates of total annual ground-water withdrawal from Oasis Valley by municipal and non-municipal users in 1996 and 1999 are 440 acre-feet and 210 acre-feet, respectively. Based on these values, natural annual ground-water discharge from Oasis Valley is about 6,100 acre-feet. Total annual discharge was 6,500 acre-feet in 1996 and 6,300 acre-feet in 1999. This quantity of natural ground-water discharge from Oasis Valley exceeds the previous estimate made in 1962 by a factor of about 2.5. Water levels were measured in Oasis Valley to gain additional insight into the ET process. In shallow wells, water levels showed annual fluctuations as large as 7 feet and daily fluctuations as large as 0.2 foot. These fluctuations may be attributed to water loss associated with evapotranspiration. In shallow wells affected by E T, annual minimum depths to water generally occurred in winter or early spring shortly after daily ET reached minimum rates. Annual maximum depths to water generally occurred in late summer or fall shortly after daily ET reached maximum rates. The magnitude of daily water-level fluctuations generally increased as ET increased and decreased as depth to water increased

278

Safety handling characteristics of high-level tritiated water  

International Nuclear Information System (INIS)

In a fusion reactor, high-level tritiated water of more than one PBq/m3 will be generated and stored in various areas. The high-level tritiated water decomposes by itself and generates mainly hydrogen, becoming tritiated hydrogen peroxide water. In order to summarize safety requirements for long-term storage of high-level tritiated water, the characteristics, such as effective G-values of hydrogen and hydrogen peroxide, pH and Oxidation-Reduction Potential (ORP), have been investigated by storing tritiated water from 5 TBq/m3 to 2 EBq/m3 for 5 years. Because the effective G-value of hydrogen increases with decreasing tritium concentration, the storage tank for a wider range of tritium concentrations requires not only depression but, also, adequate processing of the cover gases. High-level tritiated water of more than 1 PBq/m3 was acid and in some cases was in a corrosive condition; these characteristics have been maintained for 5 years. Therefore, the ORP-pH situation should be monitored periodically to avoid the corrosive condition

279

Geological events and Pliocene climate fluctuations explain the phylogeographical pattern of the cold water fish Rhynchocypris oxycephalus (Cypriniformes: Cyprinidae) in China.  

Science.gov (United States)

Background Rhynchocypris oxycephalus is a cold water fish with a wide geographic distribution including the relatively warm temperate regions of southern China. It also occurs in second- and third-step geomorphic areas in China. Previous studies have postulated that high-altitude populations of R. oxycephalus in southern China are Quaternary glacial relics. In this study, we used the mitochondrial gene Cytb and the nuclear gene RAG2 to investigate the species phylogeographical patterns and to test two biogeographic hypotheses: (1) that divergence between lineages supports the three-step model and (2) climatic fluctuations during the Quaternary resulted in the present distribution in southern China.ResultsPhylogenetic analysis detected three major matrilines (A, B, and C); with matrilines B and C being further subdivided into two submatrilines. Based on genetic distances and morphological differences, matriline A potentially represents a cryptic subspecies. The geographic division between matrilines B and C coincided with the division of the second and third geomorphic steps in China, suggesting a historical vicariance event. Pliocene climatic fluctuations might have facilitated the southwards dispersal of R. oxycephalus in matriline C, with the subsequent warming resulting in its split into submatrilines C1 and C2, leaving submatriline C2 as a relic in southern China.ConclusionsOur study demonstrates that geological events (three steps orogenesis) and climate fluctuations during the Pliocene were important factors in shaping phylogeographical patterns in R. oxycephalus. Notably, no genetic diversity was detected in several populations, all of which possessed unique genotypes. This indicates the uniqueness of local populations and calls for a special conservation plan for the whole species at the population level. PMID:25344323

Yu, Dan; Chen, Ming; Tang, Qiongying; Li, Xiaojuan; Liu, Huanzhang

2014-10-25

280

Impacts of Water Levels on Breeding Canada Geese and the Methodology for Mitigation and Enhancement in the Flathead Drainage, 1983 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

The lower Flathead River Canada goose study was initiated to determine goose population trends and the effects of water level fluctuations on Canada goose nest and brood habitat, as a result of releases from Kerr Dam. This report presents data collected during the 1983 field season (15 February to 30 September, 1983) as part of an ongoing project. (DT)

Ball, I. Joseph

1984-01-01

281

Perchlorate levels in soil and waters from the Atacama Desert.  

Science.gov (United States)

Perchlorate is an anion that originates as a contaminant in ground and surface waters. The presence of perchlorate in soil and water samples from northern Chile (Atacama Desert) was investigated by ion chromatography-electrospray mass spectrometry. Results indicated that perchlorate was found in five of seven soils (cultivated and uncultivated) ranging from 290 ± 1 to 2,565 ± 2 ?g/kg. The greatest concentration of perchlorate was detected in Humberstone soil (2,565 ± 2 ?g/kg) associated with nitrate deposits. Perchlorate levels in Chilean soils are greater than those reported for uncultivated soils in the United States. Perchlorate was also found in superficial running water ranging from 744 ± 0.01 to 1,480 ± 0.02 ?g/L. Perchlorate water concentration is 30-60 times greater than levels established by the United States Environmental Protection Agency (24.5 ?g/L) for drinking. PMID:24165784

Calderón, R; Palma, P; Parker, D; Molina, M; Godoy, F A; Escudey, M

2014-02-01

282

Measuring method for reactor water level of BWR type reactor  

International Nuclear Information System (INIS)

The present invention provides a measuring method for a reactor water level of a reactor pressure vessel (RPV) upon periodical inspection of the RPV. Namely, a supersonic sensor facing to the RPV is disposed at an upper lid nozzle of the RPV. Whether incore structures in the RPV are immersed in water or not is detected by transmission/reception of supersonic waves sent from the supersonic sensor. Since the reactor water level is detected directly by disposing the supersonic sensor to the upper lid nozzle of the RPV, the upper lid can be removed after the incore structures are completely immersed in water. Accordingly, an operator's radiation dose can be reduced greatly. (I.S.)

283

Application of the water table fluctuation method for estimating evapotranspiration at two phreatophyte-dominated sites under hyper-arid environments  

Science.gov (United States)

Shallow groundwater is primarily discharged via evapotranspiration (ETg) in arid and semi-arid riparian systems; however, the quantification of ETg remains a challenge in regional water resource assessments of such systems. In this study, the diagnostic indicators of groundwater evapotranspiration processes and the principles of applying the water table fluctuation (WTF) method to estimate ETg based on seasonal groundwater level changes were presented. These techniques were then used to investigate groundwater evapotranspiration processes at two sites dominated by phreatophytes (Tamarix ramosissima and Populus euphratica) within hyper-arid desert environments in northwestern China for the period 2010-2012. The results indicate that steady declines in the water table, which are commonly attributed to groundwater evapotranspiration, occurred at both sites during the growing season. Based on the proposed WTF method, the estimated ETg was 0.63-0.73 mm/d at the Tamarix ramosissima site and 1.89-2.33 mm/d at the Populus euphratica site during the summer months (June-August). Numerical simulations using a one-dimensional root water uptake model indicate that the seasonal variations in ETg at both sites were primarily dependent on the potential evaporation rates. Comparisons with previous studies on plant transpiration at similar sites in this area show that these results are reasonable. It is apparent that the WTF method can provide a simple and relatively inexpensive method of estimating ETg on a large scale in arid/semi-arid regions. However, there are significant uncertainties associated with time-dependent lateral flow rates, which creates a challenge when applying this method. In addition, the selection of calculation periods that show steady declines in the groundwater level can be somewhat subjective. To enhance the performance of the WTF method based on seasonal water table declines, further research on the estimation of lateral flow rates should be performed using an effective network of groundwater monitoring.

Wang, Ping; Grinevsky, Sergey O.; Pozdniakov, Sergey P.; Yu, Jingjie; Dautova, Dina S.; Min, Leilei; Du, Chaoyang; Zhang, Yichi

2014-11-01

284

Monitoring Water Level in Agriculture Using Sensor Networks  

Directory of Open Access Journals (Sweden)

Full Text Available Recent advances in communications technology andwireless sensor networks made new trends to emerge inagriculture sector. One such new trend is Precision Agriculture.In this paper we are giving brief outline of using Wireless SensorNetworks (WSN in Monitoring water level in the farm area forPrecision Agriculture. This algorithm offers a maximumopportunity of delivery of water level informationpackets/signals to base station as it also computes a threshold aswell as does calculates values based on transmission range. Thisover all computational mechanism helps us to build a robustmechanism for delivery of information to base station thus,reducing the packet loss. Our algorithm which picks up theinformation for water level can be further optimized by usingoptimization algorithms, which lead to smoothening of packetdelivery ratio, thereby increasing the packet delivery ratio bychoosing the right cost path with the help of optimizationtechniques like genetic algorithm, neural networks.

Iqbal Singh

2011-11-01

285

Water Quality and pH Levels in Aquatic Ecosystems  

Science.gov (United States)

In this fun and in depth hands-on experiment, learners test various liquid samples (distilled water, lemon juice, vinegar, and baking soda mixed with water) to determine their pH levels and identify each sample as either acid, base or neutral chemical. Then, over the course of several weeks, learners perform a number of tests and observe the affects of pH level on plants. The wrap up section of this activity discusses acid rain and its dramatic impact on aquatic animals, and tips for going further.

New Jersey

2006-01-01

286

Development of an in-vessel water level gauge for light water power reactors  

International Nuclear Information System (INIS)

The in-vessel water level gauge, in principle, is based on the measurement of the temperature distribution on the surface of a long sheathed heater-pin which is partially immersed in water. Instead of adopting the measurement with many thermocouples, a binary-coded thermocouple array consisting of differential thermocouple array consisting of differential thermocouple trains (DTCTs) is settled on or in the sheath of a heater-pin to give a binary output related to the water level. Thus, this new-type of water level gauge was named BICOTH (Binary-Coded Thermocouple-array with Heater). After feasibility tests of the method with a prototype BICOTH, two types of in-vessel BICOTH were fabricated. The performance of each type was examined under the conditions of cold water and high-temperature, high-pressure water, and encouraging results were obtained. The principle and the test results are presented

287

Measurement of water potential in low-level waste management  

International Nuclear Information System (INIS)

The measurement of soil water is important to the shallow land burial of low-level waste. Soil water flow is the principle mechanism of radionuclide transport, allows the establishment of stabilizing vegetation and also governs the dissolution and release rates of the waste. This report focuses on the measurement of soil water potential and provides an evaluation of several field instruments that are available for use to monitor waste burial sites located in arid region soils. The theoretical concept of water potential is introduced and its relationship to water content and soil water flow is discussed. Next, four major areas of soils research are presented in terms of their dependence on the water potential concept. There are four basic types of sensors used to measure soil water potential. These are: (1) tensiometers; (2) soil psychrometers; (3) electrical resistance blocks; and (4) heat dissipation probes. Tensiometers are designed to measure the soil water potential directly by measuring the soil water pressure. Monitoring efforts at burial sites require measurements of soil water over long time periods. They also require measurements at key locations such as waste-soil interfaces and within any barrier system installed. Electrical resistance blocks are well suited for these types of measurements. The measurement of soil water potential can be a difficult task. There are several sensors commercially available; however, each has its own limitations. It is important to carefully select the appropriate sensor for the job. The accuracy, range, calibration, and stability of the sensor must be carefully considered. This study suggests that for waste management activities, the choice of sensor will be the tensiometer for precise soil characterization studies and the electrical resistance block for long term monitoring programs

288

Ensemble approach for projections of return periods of extreme water levels in Estonian waters  

Science.gov (United States)

The contribution of various drivers to the water level in the eastern Baltic Sea and the presence of outliers in the time series of observed and hindcast water level lead to large spreading of projections of future extreme water levels. We explore the options for using an ensemble of projections to more reliably evaluate return periods of extreme water levels. An example of such an ensemble is constructed by means of fitting several sets of block maxima (annual maxima and stormy season maxima) with a Generalised Extreme Value, Gumbel and Weibull distribution. The ensemble involves projections based on two data sets (resolution of 6 h and 1 h) hindcast by the Rossby Centre Ocean model (RCO; Swedish Meteorological and Hydrological Institute) and observed data from four representative sites along the Estonian coast. The observed data are transferred into the grid cells of the RCO model using the HIROMB model and a linear regression. For coastal segments where the observations represent the offshore water level well, the overall appearance of the ensembles signals that the errors of single projections are randomly distributed and that the median of the ensemble provides a sensible projection. For locations where the observed water level involves local effects (e.g. wave set-up) the block maxima are split into clearly separated populations. The resulting ensemble consists of two distinct clusters, the difference between which can be interpreted as a measure of the impact of local features on the water level observations.

Eelsalu, Maris; Soomere, Tarmo; Pindsoo, Katri; Lagemaa, Priidik

2014-12-01

289

Relationship between precipitation and water-table fluctuation in a coastal dune aquifer: northeastern coast of the Buenos Aires province, Argentina  

Science.gov (United States)

The water-table fluctuation (WTF) method is one of the most widely used means to estimate aquifer recharge. In the northeastern coast of the Buenos Aires province, Argentina, the geomorphological and climatic characteristics, as well as the presence of a shallow, homogeneous unconfined aquifer, make it possible to apply this methodology. The relationship between water-table fluctuations and precipitation in a humid climate, considering its seasonal variations, is assessed. Water tables were measured monthly between February 2008 and September 2010 in a monitoring network; rainfall data were analysed. The water table rises when the accumulated precipitation between measurements is more than 53 mm/month in the dry season and more than 97 mm/month in the rainy season. The index, relating water-table fluctuations and precipitation occurring between measurements, shows that values below 0 suggest no increase in the water reserves, whereas higher values entail an increase. In the study area, where there is a lack of historical data, finding out the relationship between water-table fluctuations and precipitation will constitute a tool for groundwater use and management, and set up an early warning system for dry periods. It could also be extrapolated to other regions with similar hydrological conditions lacking in data.

Carretero, Silvina C.; Kruse, Eduardo E.

2012-12-01

290

AUTOMATED WATER LEVEL MEASUREMENTS IN SMALL-DIAMETER AQUIFER TUBES  

Energy Technology Data Exchange (ETDEWEB)

Groundwater contaminated with hexavalent chromium, strontium-90, and uranium discharges into the Columbia River along approximately 16 km (10 mi) of the shoreline. Various treatment systems have and will continue to be implemented to eliminate the impact of Hanford Site contamination to the river. To optimize the various remediation strategies, it is important to understand interactions between groundwater and the surface water of the Columbia River. An automated system to record water levels in aquifer sampling tubes installed in the hyporheic zone was designed and tested to (1) gain a more complete understanding of groundwater/river water interactions based on gaining and losing conditions ofthe Columbia River, (2) record and interpret data for consistent and defensible groundwater/surface water conceptual models that may be used to better predict subsurface contaminant fate and transport, and (3) evaluate the hydrodynamic influence of extraction wells in an expanded pump-and-treat system to optimize the treatment system. A system to measure water levels in small-diameter aquifer tubes was designed and tested in the laboratory and field. The system was configured to allow manual measurements to periodically calibrate the instrument and to permit aquifer tube sampling without removing the transducer tube. Manual measurements were collected with an e-tape designed and fabricated especially for this test. Results indicate that the transducer system accurately records groundwater levels in aquifer tubes. These data are being used to refine the conceptual and numeric models to better understand interactions in the hyporheic zone of the Columbia River and the adjacent river water and groundwater, and changes in hydrochemistry relative to groundwater flux as river water recharges the aquifer and then drains back out in response to changes in the river level.

PETERSEN SW; EDRINGTON RS; MAHOOD RO; VANMIDDLESWORTH PE

2011-01-14

291

The response of mire vegetation to water level drawdown  

Science.gov (United States)

Mires have a significant role in climate change mitigation due to their enormous carbon storage and due to the fluxes of greenhouse gases between ecosystem and the atmosphere. Mire vegetation is controlled by ecohydrology, climate and by the competition of plants on light and nutrients. The water logged conditions create a challenging environment for both vascular plants and bryophytes; therefore majority of plants growing in these habitats are highly specialized. Global warming is predicted to affect mire vegetation indirectly through increased evapotranspiration leading to decreased water table levels down to 14-22 centimeters. Water level drawdown is likely to affect the vegetation composition and consequently the ecosystem functioning of mires. Previous studies covering the first years following water table level drawdown have shown that vascular plants benefit from a lower water table and hollow-specific Sphagnum species suffer. In addition to changes in plant abundances the diversity of plant communities decreases. The lawn and hollow communities of Sphagna and sedges are found to be the most sensitive plant groups. It has been shown that surveys on vegetation changes can have different results depending on the time scale. The short and long term responses are likely vary in heterogenous mire vegetation; therefore predictions can be done more reliably with longer surveys. We applied BACI (before-after-control-impact) experimental approach to study the responses of different functional mire plant groups to water level drawdown. There are 3 control plots, 3 treatment plots with moderate water level drawdown and 3 plots drained for forestry 40 years ago as a reference. The plots are located in meso-, oligo- and ombrotrophic sites in Lakkasuo (Orivesi, Finland). The vegetation was surveyed from permanent sampling points before ditching in 2000 and during the years 2001-2003 and 2009. The data was analyzed with NMDS (PC-Ord) and DCA (CANOCO). Overall results show that the control and treatment plots were similar before the treatment which is crucial in studies conducted with BACI- experimental design. The vegetation composition in the varied between the years also in the control plots following variation in weather conditions, i.e., growing season temperature and precipitation. The year 2003 stood out with lowest water table levels and with highest coverage of the evergreen vascular plants in all plots. By 2009 there was a dramatic decrease in sedge species cover. There seems to be more changes in bryophyte cover in mesotrophic sites than in ombrotrophic ones. Especially lawn-specific Sphagnum responded to water level drawdown. To quantify the impact of water level drawdown for different plant groups we used Principal Response Curves (CANOCO). Results show that all plant groups have a different short and long term response to water level drawdown. The first three years after ditching appeared to be a disturbance state. Only after that the vegetation started to adapt to the lowered water table conditions.

Kurki, Kirsi; Laine, Jukka; Vasander, Harri; Tuittila, Eeva-Stiina

2010-05-01

292

Analysis of Water Level Dynamics in the Great Lakes of North America  

Science.gov (United States)

Anthropogenic as well as natural fluctuations such as precipitation, runoff, snowmelt, retention time, evaporation, and outflow all contribute to water levels observed in the Great Lakes. Verified hourly water level data for five stations in Lake Michigan and four stations in Lake Superior were obtained from NOAA and examined. For each station, an hourly time series ranging from 20 to 30 years in duration was decimated to produce a time series with four hour intervals. A Fourier transform was performed on each time series and the resulting frequency information displayed in a Power Spectral Density (PSD) graph. Water level records in the Great Lakes are found to exhibit power law scaling between power spectral density and period. Four distinct regions of scaling are observed with inflection points at approximately 1 day, 5 days, and 30 - 60 days. For time scales of less than one day, the power-scaling exponent (?) ranges from 0.1 to 0.5, indicating a white noise. From 1 day to 5 - 7 days, ? ranges from 1.5 to 2.6, indicating moderate to strong persistence which we propose is due to frontal movements of weather systems. On timescales between 5 days and 30 - 60 days, ? ranges from 0.1 to 0.4, again indicating a white noise which we propose is due to monthly and seasonal weather variations within the Great Lakes System. Beyond 30 - 60 days, all stations exhibit strong persistence, with ? between 1.6 and 2.7. Analysis of physical processes using nonlinear methods such as the Fourier transform allows one to determine the natural state of the environment and if the natural state fluctuates randomly (white noise) or has some underlying order (persistence). A parallel analysis approach, drawing from concepts in control theory and feedback systems, uses Bode plots in the frequency domain and can be applied to explain variations in the Power Spectral Density plots of water levels. By analyzing the pattern of change in amplitude and phase across frequencies in a Bode plot, the dynamic properties of a system can be discerned. Bode plots draw a window into the underlying internal dynamics of the system answering questions such as the presence of time delays, the stability of the physical system, and the extent to which the system is acting as an integrator. For example, the Power Spectral Density plot of water levels in which the Beta value is near ? = 2 for time intervals from 1 day to 5 - 7 days suggests that the system is acting as an integrator over this time scale. Changes in water levels and tides have been used as an index for physical parameters such as temperature, density, and circulation (Keeling and Whorf, 1997; Denny and Paine, 1998). Long term 1/f noise (environmental noise) in the physical environment has been shown to affect populations of species embedded in these environments. Variations observed in the changing ? of water levels (environmental noise) may have biological impacts on population dynamics of organisms, including rates of survival or extinction (Batchhelder and Powell 2002). The application of Bode analysis and control theory concepts to population dynamics may provide additional insight into the underlying dynamics of the response of a population to noise found within the physical environment. Knowledge of the biological-physical coupling and the impact of environmental noise (as observed in water level data) in this aquatic environment are needed to understand the complex ecosystem dynamics.

Smigelski, J. R.; Tebbens, S. F.; Barton, C. C.

2008-12-01

293

Global secular changes in different tidal high water, low water and range levels  

Science.gov (United States)

Tides exert a major control on the coastal zone by influencing high sea levels and coastal flooding, navigation, sediment dynamics, and ecology. Therefore, any changes to tides have wide ranging and important implications. In this paper, we uniquely assess secular changes in 15 regularly used tidal levels (five high water, five low water and five tidal ranges), which have direct practical applications. Using sea level data from 220 tide gauge sites, we found changes have occured in all analyzed tidal levels in many parts of the world. For the tidal levels assessed, between 36% and 63% of sites had trends significantly different (at 95% confidence level) from zero. At certain locations, the magnitude of the trends in tidal levels were similar to trends in mean sea level over the last century, with observed changes in tidal range and high water levels of over 5 mm yr-1 and 2 mm yr-1, respectively. More positive than negative trends were observed in tidal ranges and high water levels, and vice versa for low water levels. However we found no significant correlation between trends in mean sea level (MSL) and any tidal levels. Spatially coherent trends were observed in some regions, including the north-east Pacific, German Bight and Australasia, and we also found that differences in trends occur between different tidal levels. This implies that analyzing different tidal levels is important. Because changes in the tide are widespread and of similar magnitude to MSL rise at a number sites, changes in tides should be considered in coastal risk assessments.

Mawdsley, Robert J.; Haigh, Ivan D.; Wells, Neil C.

2015-02-01

294

CAN FLUORIDATION AFFECT WATER LEAD LEVELS AND LEAD NEUROTOXICITY?  

Science.gov (United States)

Recent reports have attempted to show that certain approaches to fluoridating potable water is linked to increased levels of lead(II) in the blood. We examine these claims in light of the established science and critically evaluate their significance. The completeness of nexafluo...

295

Comparison Between Water Level and Precipitation in Rio Negro Basin  

Science.gov (United States)

The Amazon Basin holds a lot of difficulties for providing data that enable regional researching works, because of its large extension and for having areas, whose access is very difficult. Remote sensing data presents an excellent way for monitoring the Amazon Basin and collecting data for researches. This current study aims matching radar altimetry data from the JASON-2, with the rainfall data from the TRMM satellite in order to analyze the relation between the water level and the precipitation in two different points along the Rio Negro Basin. After data analysis, it was possible noting a difference on the responding process for both regions. Whilst at the NEGRO_089_03 station (located in the city of São Gabriel da Cachoeira) the graphic of precipitation and water level were very similar, in NEGRO_063 station (located in the city of Manaus) the graphic showed a two month discrepancy due to the difference of the river's bottom size in both regions, at NEGRO_089_03's area for having a smaller river and the water level rises faster, whereas in NEGRO_063 the water level takes about two months to respond to precipitation.

Figliuolo, G. C.; Santos Da Silva, J.; Calmant, S.; Seyler, F.; Correia, F.; Oliveira, R. J.

2013-12-01

296

TRIHALOMETHANE LEVELS IN HOME TAP WATER AND SEMEN QUALITY  

Science.gov (United States)

Trihalomethane Levels in Home Tap Water and Semen Quality Laura Fenster, 1 Kirsten Waller, 2 Gayle Windham, 1 Tanya Henneman, 2 Meredith Anderson, 2 Pauline Mendola, 3 James W. Overstreet, 4 Shanna H. Swan5 1California Department of Health Services, Division of Environm...

297

First record of beachrock on Black Sea coast of Turkey: Implications for Late Holocene sea-level fluctuations  

Science.gov (United States)

We present new data on the diagenetic characteristics, subsurface nature and radiocarbon ages of beachrock from the Thracian Black Sea coast of Turkey, indicative of sea-level changes and climatic conditions favoring lithification of beach sands between 5.4 ka and 3.5 ka cal BP. Micrite coatings and succeeding meniscus cements typify diagenetic history and suggest a two-stage cementation over this timeframe. The early cements are typical of upper intertidal zone when the sea-level was likely similar to that of today. The ensuing intergranular bridges refer to an approximate 2 m decline in sea-level, favoring downward percolation of meteoric waters related to subaerial exposure, marked by a reduction in Mg concentration and dissolution pits on early cement coatings. Formation of beachrock during this bimillennial period could be associated with relatively drier conditions promoting the precipitation of connective cements.

Erginal, Ahmet Evren; Ekinci, Yunus Levent; Demirci, Alper; Bozcu, Mustafa; Ozturk, Muhammed Zeynel; Avcioglu, Mustafa; Oztura, Erdal

2013-08-01

298

Water level oscillations in Monterey Bay and Harbor  

Directory of Open Access Journals (Sweden)

Full Text Available Seiches are normal modes of water bodies responding to geophysical forcings with potential to significantly impact ecology and maritime operations. Analysis of high-frequency (1 Hz water level data in Monterey California identifies Harbor modes between 10 and 120 s that are attributed with specific geographic features. It found that modal amplitude modulation arises from cross-modal interaction and that offshore wave energy is a primary driver of these modes. Synchronous coupling between modes is observed to significantly impact dynamic water levels. At lower frequencies between 15 and 60 min modes are independent of offshore wave energy, yet are continuously present. This is unexpected since seiches normally dissipate after cessation of the driving force, indicating an unknown forcing. Spectral and kinematic estimates of these low frequency oscillations supports the idea that a persistent anticyclonic mesoscale gyre adjacent to the Bay is a potential mode driver, while discounting other sources.

J. Park

2014-11-01

299

Comparison of three approaches to model grapevine organogenesis in conditions of fluctuating temperature, solar radiation and soil water content  

Science.gov (United States)

Background and Aims There is increasing interest in the development of plant growth models representing the complex system of interactions between the different determinants of plant development. These approaches are particularly relevant for grapevine organogenesis, which is a highly plastic process dependent on temperature, solar radiation, soil water deficit and trophic competition. Methods The extent to which three plant growth models were able to deal with the observed plasticity of axis organogenesis was assessed. In the first model, axis organogenesis was dependent solely on temperature, through thermal time. In the second model, axis organogenesis was modelled through functional relationships linking meristem activity and trophic competition. In the last model, the rate of phytomer appearence on each axis was modelled as a function of both the trophic status of the plant and the direct effect of soil water content on potential meristem activity. Key Results The model including relationships between trophic competition and meristem behaviour involved a decrease in the root mean squared error (RMSE) for the simulations of organogenesis by a factor nine compared with the thermal time-based model. Compared with the model in which axis organogenesis was driven only by trophic competition, the implementation of relationships between water deficit and meristem behaviour improved organogenesis simulation results, resulting in a three times divided RMSE. The resulting model can be seen as a first attempt to build a comprehensive complete plant growth model simulating the development of the whole plant in fluctuating conditions of temperature, solar radiation and soil water content. Conclusions We propose a new hypothesis concerning the effects of the different determinants of axis organogenesis. The rate of phytomer appearance according to thermal time was strongly affected by the plant trophic status and soil water deficit. Futhermore, the decrease in meristem activity when soil water is depleted does not result from source/sink imbalances. PMID:20852307

Pallas, B.; Loi, C.; Christophe, A.; Cournède, P. H.; Lecoeur, J.

2011-01-01

300

Effects of Water Levels on Productivity of Canada Geese in the Northern Flathead Valley, 1984 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

Operation of Hungry Horse Dam on the South Fork Flathead River causes sporadic level fluctuations along the main stem Flathead River. Seasonal water level fluctuations and substantial habitat losses have occurred as a result of construction and operation of Kerr Dam, which regulates Flathead Lake. These fluctuations may impact goose populations through flooding or erosion of nesting and brood-rearing habitats, and increased susceptibility of nests and young to predation. The number, location, and success of goose nests were determined through pair surveys and nest searches. Counts of indicated pairs suggest there were 73-125 occupied nests in the study area; 44 were located in 1984. Twenty were island ground nests, 19 were tree nests, and 5 were on man-made structures. Hatching success was 76 percent. Sixty-one percent of all nests were in deciduous forest habitat; 87 percent were on riparian bench or island landforms. Seventy-four percent of all nests were within 5 m of the seasonal high water mark (HWM) and 85 percent of ground nests were 1 m or less above the HWM. Production, habitat use, and distribution of broods were documented through aerial, boat, ground, and observation tower surveys. 28 refs., 10 figs., 4 tabs.

Casey, Daniel

1985-02-01

301

An analysis of the water-level monitoring system for a boiling-water reactor  

International Nuclear Information System (INIS)

The water-level instrumentation system is very important to the overall safety of a BWR. This system is being monitored by the Safety Parameter Display System (SPDS) that is being installed in Georgia Power Company's Plant Hatch. One of the most significant functions of the SPDS is the comparison of redundant instrument readings and formation of the best estimate of each parameter from those readings which are consistent. When comparing water-level instrument readings, it is necessary to correct the individual readings for differences between current and calibration conditions as well as for differences between calibration conditions for the multiple instruments. This paper documents the examination of the water-level instrumentation system at Plant Hatch and presents the development of the equations that were used to determine the differences between indicated and actual water levels. (author)

302

Modelling the impact of climate change on groundwater in the UK. Stage 2 report, using an unsaturated zone transfer function to model groundwater level fluctuations  

OpenAIRE

This report describes work carried out as part of the second stage of the joint BGS-CEH project “Modelling the impact of climate change on groundwater in the UK”. The work described in the report involved testing and developing a simple approach to the reproduction of historical groundwater level fluctuations. The technique makes use of an unsaturated zone transfer function to represent delayed recharge. The model was used to replicate long-term groundwater level records fr...

O Dochartaigh, B. E.

2001-01-01

303

Set norms of the radioactive pollution safety levels of water and bottom sediments in water objects  

International Nuclear Information System (INIS)

Safety standards are proposed permitting to optimize the monitoring of rivers and water reservoirs for man-made radioactive substances contents. Concepts of maximum safe concentration and reference concentration of radionuclides in water, maximum contamination level of bottom sediments are introduced. Calculation of the standards for certain radionuclides is presented. Use of the proposed standards will make it possible to unify the monitoring of water objects for contamination in various situations and to protect population

304

BETCO: A Computer Program for the Removal of Barometric and Earth Tide Effects From Water Levels  

Science.gov (United States)

Barometric pressure effects in long-term water level measurements can mask drawdown responses to well tests and natural stimuli. Noise caused by barometric pressure and earth tide effects complicates analysis of pressure response data using diagnostic pressure derivative plots. A computer program has been developed to remove fluctuations in groundwater levels induced by changes in barometric pressure and earth tides. The program implements a regression deconvolution method to obtain a barometric response function and remove the barometric pressure and earth tide effects from the groundwater level data. Using the barometric response function yields a better residual or corrected head than using a constant barometric efficiency. The graphical response function can be used to diagnose aquifer type and well skin effects. A modification of the regression deconvolution has been implemented to simultaneously remove earth tide effects as well as barometric effects on water levels. The removal of the earth tide effects is provided as a beta feature. The software has been applied to 13 water level data sets at the Waste Isolation Pilot Plant in Carlsbad, NM. The results are compared to a constant barometric efficiency correction method. The freeware software is available as an install wizard for Windows XP and 2000. As of submission, all results output from BETCO are considered preliminary, please do not cite. The code is under continued development and will be qualified per the Sandia National Laboratories WIPP Software QA Plan requirements. This research is funded by WIPP programs administered by the Office of Environmental Management (EM) of the U.S. Department of Energy. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Toll, N.; Rasmussen, T. C.

2005-12-01

305

The Water Resources Division water level recorder rental program; history and operation  

Science.gov (United States)

The U.S. Geological Survey introduced a new water level recorder in the early 1960 's to automate computation of streamflow records. At the same time it developed a rental program as a means of providing the recorders to field offices. This report documents the experience gained over the past 20 years and offers suggestions for operation of a rental program in the future, as preparation is made to introduce a third generation of water level recorders. (USGS)

Jeffers, S.R.; Wagner, C.R.

1984-01-01

306

Holocene lake level fluctuations of a small alpine lake in the Qilian Mountains, NW China: a comparison of chironomid, ostracod, pollen and geochemistry data.  

Science.gov (United States)

A core of 14 m length was drilled in a small alpine lake in the Qilian Mountains, NW China. The lake Luanhaizi has a drainage area of about 30 km2 and is situated at an altitude of 3200 m which represents the altitude of the present regional upper timberline. Due to the small size of the open-basin lake (surface area about 1 km2) and the sharply outlined catchment area the lake is regarded as a very sensitively and rapidly responding ecosystem. Analyses of ostracod shells, head capsules of larval chironomids and pollen and spores were conducted and the organic and carbonate content (LOI), element concentrations and magnetic susceptibility of core samples determined. Ostracod taxa mainly comprise Candona candida, C. neglecta, C. rawsoni, Cyclocypris ovum, Cypridopsis vidua, Fabaeformiscandona caudata, F. danielopoli, F. hyalina, Herpetocypris chevreuxi, Heterocypris salina, Ilyocypris cf. bradyi, I. echinata, I. lacustris and Limnocythere inopinata. They may be used to distinguish periods of low lake levels corresponding to a dense cover of aquatic plants at the lake bottom from stages of higher lake levels and a corresponding decrease in macrophytes at the core site. Chironomid taxa belonging to Chironomus, Cladopelma, Glyptotendipes, Micropsectra, Paratanytarsus, Polypedilum, Psectrocladius and Tanytarsus further provide information on variations in benthic oxygen availability and lake level fluctuations. Several units of the core show high abundances of pollen and spores of higher aquatic and wetland plants and fungi (Cyperaceae, Hippuris, Myriophyllum and Glomus) indicating low lake levels. In contrast, algae such as Botryococcus, Pediastrum and Tetraedron were regarded to reflect higher water levels. Typha angustifolia-type, Typha latifolia, Alisma and Potamogeton were recorded in low abundances as well. The organic content of core samples averages 6 % displaying four alternating stages of distinct minima and maxima. Lowest values of about 1 % occur at the core base whereas the organic content rises to 16 % at maximum near the top. The carbonate content displays a similar pattern with strong shifts ranging from 3 to 31%. The results of the investigation of the sediment core from the alpine lake in the Qilian Mountains were presented and the validity of single proxies with respect to lake level changes discussed.

Mischke, S.; Herzschuh, U.

2003-04-01

307

Wave-induced mass transport affects daily Escherichia coli fluctuations in nearshore water  

Science.gov (United States)

Characterization of diel variability of fecal indicator bacteria concentration in nearshore waters is of particular importance for development of water sampling standards and protection of public health. Significant nighttime increase in Escherichia coli (E. coli) concentration in beach water, previously observed at marine sites, has also been identified in summer 2000 from fixed locations in waist- and knee-deep waters at Chicago 63rd Street Beach, an embayed, tideless, freshwater beach with low currents at night (approximately 0.015 m s–1). A theoretical model using wave-induced mass transport velocity for advection was developed to assess the contribution of surface waves to the observed nighttime E. coli replenishment in the nearshore water. Using average wave conditions for the summer season of year 2000, the model predicted an amount of E. coli transported from water of intermediate depth, where sediment resuspension occurred intermittently, that would be sufficient to have elevated E. coli concentration in the surf and swash zones as observed. The nighttime replenishment of E. coli in the surf and swash zones revealed here is an important phase in the cycle of diel variations of E. coli concentration in nearshore water. According to previous findings in Ge et al. (Environ. Sci. Technol. 2010, 44, 6731–6737), enhanced current circulation in the embayment during the day tends to displace and deposit material offshore, which partially sets up the system by the early evening for a new period of nighttime onshore movement. This wave-induced mass transport effect, although facilitating a significant base supply of material shoreward, can be perturbed or significantly influenced by high currents (orders of magnitude larger than a typical wave-induced mass transport velocity), current-induced turbulence, and tidal forcing.

Ge, Zhongfu; Whitman, Richard L.; Nevers, Meredith B.; Phanikumar, Mantha S.

2012-01-01

308

Conformational fluctuations of a protein-DNA complex and the structure and ordering of water around it  

Science.gov (United States)

Protein-DNA binding is an important process responsible for the regulation of genetic activities in living organisms. The most crucial issue in this problem is how the protein recognizes the DNA and identifies its target base sequences. Water molecules present around the protein and DNA are also expected to play an important role in mediating the recognition process and controlling the structure of the complex. We have performed atomistic molecular dynamics simulations of an aqueous solution of the protein-DNA complex formed between the DNA binding domain of human TRF1 protein and a telomeric DNA. The conformational fluctuations of the protein and DNA and the microscopic structure and ordering of water around them in the complex have been explored. In agreement with experimental studies, the calculations reveal conformational immobilization of the terminal segments of the protein on complexation. Importantly, it is discovered that both structural adaptations of the protein and DNA, and the subsequent correlation between them to bind, contribute to the net entropy loss associated with the complex formation. Further, it is found that water molecules around the DNA are more structured with significantly higher density and ordering than that around the protein in the complex.

Sinha, Sudipta Kumar; Bandyopadhyay, Sanjoy

2011-12-01

309

Quadratic controller syntheses for the steam generator water level  

International Nuclear Information System (INIS)

The steam generator water level, (SGWL), control problem in the pressurized water reactor of a nuclear power plant is considered from robust control techniques point of view. The plant is a time-varying system with a non minimum phase behavior and an unstable open-loop response. The time-varying nature of the plant due to change in operating power is taken into account by including slowly time-varying uncertainty in the model. A linear Time-Invariant, (LTI) guaranteed cost quadratic stabilizing controller is designed in order to address some of the particular issues arising for such a control problem. (author)

310

Quality Level of Bottled Drinking Water Consumed in Saudi Arabia  

Directory of Open Access Journals (Sweden)

Full Text Available The quality of drinking water is a universal health concern and access to safe water is a fundamental human right. Many national and international organizations set certain parameters and levels for Bottled Drinking Water (BDW to ensure their quality. The present work aims to analyze the quality of various brands of BDW used in Saudi Arabia and to compare the quality levels to the BDW standards. One hundred and twenty six samples of 54 different BDW brands were collected from the Saudi market. The quality level parameters were analyzed using portable meters for pH, EC and TDS; spectrophotometer, HACH DR-2800 for F, SO4 and NO3; Inductively Coupled Plasma (ICP Mass Spectrometer (MS and atomic emission spectrometer (AES for elemental analysis. To evaluate the quality level parameters of BDW, the parameters were classified as following: (1 Parameters and substances affect the quality of BDW (pH, EC, TDS, HCO3, F, NO3 and SO4. (2 Macronutrients (Ca, K, Mg and Na. (3 Micronutrients-trace elements (Co, Cr, Cu, Fe, Mo, Se and Zn, (4 Potentially essential elements that have some beneficial health effects (B, Mn, Ni and V and (5 Toxic elements (Al, As, Cd, Hg, Pb, Th and U using Inductively coupled plasma-mass spectrometry, ICP-MS. The concentrations of the detected elements were compared with the Golf and international standard like World Health Organization.

Ashraf E.M. Khater

2014-01-01

311

Effects of Water Levels on Productivity of Canada Geese in the Northern Flathead Valley, 1985 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

Operation of Hungry Horse Dam on the South Fork Flathead River causes sporadic water level fluctuations along the main stem Flathead River. Changes in chronology of seasonal water level fluctuations and substantial habitat losses have occurred as a result of construction and operation of Kerr Dam, which regulates Flathead Lake. These fluctuations may impact goose populations through flooding and erosion of nesting and brood-rearing habitats, and increased susceptibility of nests and young to predation. The number, location, and success of goose nests were determined through pair surveys and nest searches. Our 1985 pair count data indicated that 95 to 143 nests may have been present. Hatching success for 1985 nests (55%) was low compared to long-term averages for the region. Predation was the predominant cause of ground nest failure (25 nests); we documented 2 nest failures due to flooding. The maximum gosling count in the study area for 1985 was 197. Six key brood-rearing areas were identified. Most (80%) sites were located in the herbaceous or pasture cover type and the riparian bench landform. Analysis of aerial photographs taken prior to construction of Kerr Dam documented the loss of 1859 acres of habitat along the north shore of Flathead Lake. Losses were attributed to inundation and to continuing erosion due to operation of Kerr Dam. Lake and river water level regimes were compared with the chronology of important periods in the nesting cycle. Low lake levels in May and early June coincide with the breed-rearing period. Mudflats are heavily used by broods, but their effect on survival must still be documented. Preliminary recommendations to protect and enhance Canada goose habitat and production are being developed.

Casey, Daniel

1986-04-01

312

Quantifying Water Level Change Through Time in the North American Great Lakes  

Science.gov (United States)

Anthropogenic and natural fluctuations including precipitation, runoff, snowmelt, water retention time, evaporation, and outflow all contribute to changes in water levels recorded in the North American Great Lakes. Changes in water levels and tides have been used as an index for physical parameters such as temperature, density, and circulation (Keeling and Whorf, 1997; Denny and Paine, 1998). In this study, NOAA verified hourly water level data ranging from 20 to 30 years in duration for five stations in Lake Michigan and four stations in Lake Superior were analyzed. Power Spectral Density calculated from a Fourier transform of the time series were found to exhibit power law scaling. The power-scaling exponent (?) was determined by fitting a power function to a log-log plot of frequency (f) or period (1/f) versus power in the frequency domain. Four distinct regions of scaling are observed with inflection points at approximately 1 day, 5 days, and 30 - 60 days. For time scales of less than one day, the power-scaling exponent (?) ranges from 0.1 to 0.5, indicating a white noise. From 1 day to 5 - 7 days, ? ranges from 1.5 to 2.6, indicating moderate to strong persistence which we propose is due to frontal movements of weather systems. On timescales between 5 days and 30 - 60 days, ? ranges from 0.1 to 0.4, again indicating a white noise which we propose is due to monthly and seasonal weather variations within the Great Lakes System. Beyond 30 - 60 days, all stations exhibit persistence, with ?-values between 1.6 and 2.7.

Tebbens, S. F.; Smigelski, J. R.; Barton, C. C.

2011-12-01

313

Analytical approach for predicting fresh water discharge in an estuary based on tidal water level observations  

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Full Text Available As the tidal wave propagates into an estuary, the tidally averaged water level tends to rise in landward direction due to the density difference between saline and fresh water and the asymmetry of the friction. The effect of friction on the residual slope is even more remarkable when accounting for fresh water discharge. In this study, we investigate the influence of river discharge on tidal wave propagation in the Yangtze estuary with specific attention to residual water level slope. This is done by using a one-dimensional analytical model for tidal hydrodynamics accounting for the residual water level. We demonstrate the importance of the residual slope on tidal dynamics and use it to improve the prediction of the tidal propagation in estuaries (i.e., tidal damping, velocity amplitude, wave celerity and phase lag, especially when the influence of river discharge is significant. Finally, we develop a new inverse analytical approach for estimating fresh water discharge on the basis of tidal water level observations along the estuary, which can be used as a tool to obtain information on the river discharge that is otherwise difficult to measure in the tidal region.

H. Cai

2014-06-01

314

Primary collector wall local temperature fluctuations in the area of water-steam phase boundary  

Energy Technology Data Exchange (ETDEWEB)

A limited number of temperature sensors could be installed at the primary collector surface in the area of water - steam phase boundary. The surface temperatures as well WWER 440 steam generator process data were measured and stored for a long time and off-line evaluated. Selected results are presented in the paper. (orig.). 2 refs.

Matal, O.; Klinga, J.; Simo, T. [Energovyzkum Ltd., Brno (Switzerland)

1995-12-31

315

Primary collector wall local temperature fluctuations in the area of water-steam phase boundary  

International Nuclear Information System (INIS)

A limited number of temperature sensors could be installed at the primary collector surface in the area of water - steam phase boundary. The surface temperatures as well WWER 440 steam generator process data were measured and stored for a long time and off-line evaluated. Selected results are presented in the paper. (orig.)

316

The Water Level Fall of Lake Megali Prespa (N Greece): an Indicator of Regional Water Stress Driven by Climate Change and Amplified by Water Extraction?  

Science.gov (United States)

The Mediterranean stands out globally due to its sensitivity to (future) climate change, with future projections predicting an increase in excessive drought events and declining rainfall. Regional freshwater ecosystems are particularly threatened: precipitation decreases, while extreme droughts increase and human impacts intensify (e.g. water extraction, drainage, pollution and dam-building). Many Mediterranean lake-wetland systems have shrunk or disappeared over the past two decades. Protecting the remaining systems is extremely important for supporting global biodiversity and for ensuring sustainable water availability. This protection should be based on a clear understanding of lake-wetland hydrological responses to natural and human-induced changes, which is currently lacking in many parts of the Mediterranean. The interconnected Prespa-Ohrid Lake system is a global hotspot of biodiversity and endemism. The unprecedented fall in water level (~8m) of Lake Megali Prespa threatens this system, but causes remain debated. Modelling suggests that the S Balkan will experience rainfall and runoff decreases of ~30% by 2050. However, projections revealing the potential impact of these changes on future lake level are unavailable as lake regime is not understood. A further drop in lake level may have serious consequences. The Prespa Lakes contribute ~25% of the total inflow into Lake Ohrid through underground karst channels; falling lake levels decrease this discharge. Lake Ohrid, in turn, feeds the Drim River. This entire catchment may therefore be affected by falling lake levels; its water resources are of great importance for Greece, Albania, FYROM and Montenegro (e.g. tourism, agriculture, hydro-energy, urban & industrial use). This new work proves that annual water level fluctuations of Lake Megali Prespa are predominantly related to precipitation during the first 7 months (Oct-Apr) of the hydrological year (Oct-Sep). Lake level is very sensitive to regional and Mediterranean wet-dry events during this period. There are robust indications for a link between lake level and the North Atlantic Oscillation, which is known to strongly influence Mediterranean winter precipitation. Hydro-climatic records show a complicated picture, but tentatively support the conclusion that the unprecedented lake level fall is principally related to climate change. The available fluvial discharge record and most existing snowfall records show statistically significant decreases in annual averages. Annual rainfall only shows a statistically significant decrease of the 25th percentile; 7-month rainfall (Oct-Apr) additionally shows a statistically significant but non-robust decrease of the mean. The modest amount of water extraction (annually: ~14*103m3, ~0.004% of total lake volume) exerts a progressive and significant impact on lake level over the longer term, accounting for ~25% of the observed fall. Lake level lowering ends when lake-surface area shrinkage has led to a decrease in lake-surface evaporation that is equivalent to the amount of water extracted. The adjustment of lake level to stable extraction rates requires two to three decades. This work aims to steer adaptation and mitigation strategies by informing on lake response under different climate change and extraction scenarios. Lake protection is a cost effective solution for supporting global biodiversity and for providing sustainable water resources.

van der Schriek, Tim; Giannakopoulos, Christos

2014-05-01

317

Predicting the residual aluminum level in water treatment process  

Directory of Open Access Journals (Sweden)

Full Text Available In water treatment processes, aluminum salts are widely used as coagulation chemical. High dose of aluminum has been proved to be at least a minor health risk and some evidence points out that aluminum could increase the risk of Alzheimer's disease thus it is important to minimize the amount of residual aluminum in drinking water and water used at food industry. In this study, the data of a water treatment plant (WTP was analyzed and the residual aluminum in drinking water was predicted using Multiple Linear Regression (MLR and Artificial Neural Network (ANN models. The purpose was to find out which variables affect the amount of residual aluminum and create simple and reliable prediction models which can be used in an early warning system (EWS. Accuracy of ANN and MLR models were compared. The new nonlinear scaling method based on generalized norms and skewness was used to scale all measurement variables to range [?2...+2] before data-analysis and modeling. The effect of data pre-processing was studied by comparing prediction results to ones achieved in an earlier study. Results showed that it is possible to predict the baseline level of residual aluminum in drinking water with a simple model. Variables that affected the most the amount of residual aluminum were among others: raw water temperature, raw water KMnO4 and PAC / KMnO4-ratio. The accuracies of MLR and ANN models were found to be almost equal. Study also showed that data pre-processing affects to the final prediction result.

J. Tomperi

2012-06-01

318

Dendrochronological evaluation of historic changes in Lake Stirniai (Lithuania) water level  

International Nuclear Information System (INIS)

Full text: Dendrochronological research was carried out on Pinus sylvestris L. timber extracted from Lake Stirniai (55o15'04'' latitude (N) and 25o38'49'' longitude (E)). As a result, the tree ring width floating chronology spanning 213 years was compiled. Radiocarbon dating of the samples indicated that pines grew from 1103 ± 80 AD to 1315 ± 80 AD. Fragments of stems and roots of pines were found waterlogged in 1 m water layer. It means that in the Medieval Warm Period, the ground water level in the habitat of archaeological pines was below the nowadays lake level for at least by 1 m. The growth conditions became unfavourable in ? 1270 ± 80 AD. At the end of the 13th century the climate became damper, lake transgression started, the trees of Scots pine became dry. The basic cause of transgression seems to be the bogged bed of the rivulet Stirna flowing out of the lake. This phenomenon was caused by the changed climate conditions. The formant analysis of the radial increase of the stems of archaeological Scots pine in Lake Stirniai revealed 52.9; 30.3; 21.1; 17.5; 15.0; 11.2 year long-term fluctuation cycles. Comparison of the obtained data with the present cycles is foreseen. (author)

319

Radon concentration levels in ground water from Toluca, Mexico.  

Science.gov (United States)

Concentration levels of 222Rn have been analysed in water samples from deep wells of the aquifers around the City of Toluca, Mexico. The 222Rn source is the decay of 226Ra within the solid matrix of the aquifer. With a half life of 1600 years the 226Ra continuously releases 222Rn to the pores, from which it diffuses into the main body of water. This paper describes the methods used for sampling and measuring solubilized and 226Ra-supported 222Rn in the water samples, in order to evaluate possible health hazards due to the presence of radon in the drinking water supplies. The relationship of 222Rn with the hydrogeologic characteristics of the zone is also described. The analytical method involves laboratory extraction of 222Rn into toluene. Alpha disintegrations of 222Rn and contributions from short-lived daughters are counted by the liquid scintillation technique. The system was calibrated using a 226Ra standard solution. Results up to 11.3 Bq/l of 222Rn were obtained in the water samples. PMID:8469957

Olguin, M T; Segovia, N; Tamez, E; Alcántara, M; Bulbulian, S

1993-03-25

320

On the evaluation of environmental condition by the level of fluctuating asymmetry in anuran amphibian of lake frog (Rana ridibunda as an example ?? ?????? ????????? ?????????? ????? ?? ?????? ????????????? ?????????? ? ?????????? ??????? ?? ??????? ??????? ??????? (Rana ridibunda  

Directory of Open Access Journals (Sweden)

Full Text Available The possibility of the usage of environmental condition evaluation by the level of fluctuating asymmetry in anuram amphibians is discussed. On the basis of original results and literature cited the conclusion is made that similar studies must be provided with the thought-over choice of studied objects and used characteristics as well as by the objective search of the causes with the account of all the assemblage of ecological factors acting on the development of an organism.??????????? ??????????? ????????????? ?????? ????????? ?????????? ????? ?? ?????? ????????????? ?????????? ? ?????????? ???????????. ?? ????????? ??????????? ??????????? ? ?????????? ???????????? ?????????? ???????? ?????, ??? ???????? ?????? ?????? ?????????????? ??????????? ??????? ???????? ???????????? ? ???????????? ?????????, ? ????? ??????????? ??????? ?????? ? ?????? ???? ???????????? ????????????? ????????, ??????????? ?? ???????? ??????????.

Lada Georgiy Arcadyevich

2012-11-01

321

The Effect of Water Level on The Effectiveness of Sediment Flushing  

OpenAIRE

This research is focused on determining the effective flushing water level in pressure flushing activity at storage sedimen based on the hydraulic physical model test in the laboratory. The effective water level is the elevation of water level in sediment flushing which result in the highest concentration of sediment scours. Effective flushing water level is the elevation of water level near the top layer of sediment deposit which can trigger the erosion of the top layer of sediment so that i...

Suripin, S.; Pranoto Samto Atmodjo

2012-01-01

322

Seasonal changes in ground-water quality and ground-water levels and directions of ground-water movement in southern Elmore County, southwestern Idaho, including Mountain Home Air Force Base, 1990-1991  

Science.gov (United States)

The study area is located in southern Elmore County, southwestern Idaho, and includes the Mountain Home Air Force Base located approximately 10 mi southwest of the city of Mountain Home. Chemical analyzes have been made periodically since the late 1940's on water samples from supply wells on the Air Force Base. These analyses indicate increases in specific conductance and in concentrations of nitrogen compounds, chloride, and sulfate. The purposes of this report, which was prepared in cooperation with the Department of the Air Force, are to describe the seasonal changes in water quality and water levels and to depict the directions of ground-water movement in the regional aquifer system and perched-water zones. Although data presented in this report are from both the regional ground-water system and perched-water zones, the focus is on the regional system. A previous study by the U.S. Geological Survey (Parliman and Young, 1990) describes the areal changes in water quality and water levels during the fall of 1989. During March, July, and October 1990, 141 wells were inventoried and depth to water was measured. Continuous water-level recorders were installed on 5 of the wells and monthly measurements of depth to water were made in 17 of the wells during March 1990 through February 1991. Water samples from 33 wells and 1 spring were collected during the spring and fall of 1990 for chemical analyses. Samples also were collected monthly from 11 of those wells during April to September 1990 (table 1). Selected well-construction and water-use data and measurements of depth to water for 141 wells are given in table 2 (separated sheets in envelope). Directions of ground-water movement and selected hydrographs showing seasonal fluctuations of water levels in the regional ground-water system and perched-water zones are shown on sheet 2. Changes in water levels in the regional ground-water system during March to October 1990 are shown on sheet 2.

Young, H.W.; Parliman, D.J.; Jones, Michael L.

1992-01-01

323

Response of the Apodi-Mossoró estuary-incised valley system (NE Brazil to sea-level fluctuations  

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Full Text Available This study focuses on the Quaternary sea level changes in the Apodi-Mossoró Estuary and adjacent shelf, Northeastern Brazil, based on the analysis of high-resolution seismic profiles, integrated with echosounder, SRTM and satellite image data. We use these data to develop a relative stratigraphy. An incised-valley extending from the Apodi-Mossoró Estuary onto the shelf dominates the investigated area. In very shallow waters (down to 10 m depth the channel lies mainly in a NW-SE direction, changing to NE-SW in waters below10 m, in the form of a J-shaped valley. The southern flank of the shallow channel presents an abrupt morphology, probably determined by a residual scarp due to neotectonic reactivation of a pre-existing fault. This incised-valley can be correlated with a former river valley formed during the late Pleistocene fall in sea-level. The base-level change related to this drop in sea level can be regionally expressed on seismic lines as a laterally-continuous stratigraphic surface named Horizon I, interpreted as representing the sub-aerial exposure of the continental shelf. Many incised valleys were excavated on this exposed shelf, including that of the Apodi-Mossoró Estuary and its incised valley system. This incised valley has lain buried since the Holocene transgression. The Holocene sediments present sub-horizontal layers, or they have filled the incised valley with oblique features.Este estudo utiliza a integração de dados sísmicos de alta resolução, batimétricos, SRTM e imagens de satélite para desenvolvimento da estratigrafia relativa visando entender as variações do nível do mar durante o Quaternário no estuário do rio Apodi-Mossoró e plataforma adjacente, nordeste do Brasil. A principal feição identificada foi um canal submerso, na plataforma interna, parcialmente preenchido, provavelmente relacionado com o sistema de vales incisos formado durante o rebaixamento do nível do mar no Pleistoceno. O canal apresenta duas direções principais (NW-SE e NE-SW, em forma da letra J, aparentemente controladas pelas estruturas tectônicas da Bacia Potiguar. A margem oeste do canal é relativamente soerguida em relação à margem leste. Com base nos dados sísmicos foi possível identificar uma descontinuidade presente em toda a área, interpretada como o limite Pleistoceno/Holoceno, bem como sismofácies referentes a padrões de preenchimento e sedimentação do canal submerso e da plataforma durante a subida do nível do mar no Holoceno.

Helenice Vital

2010-01-01

324

Response of the Apodi-Mossoró estuary-incised valley system (NE Brazil) to sea-level fluctuations  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este estudo utiliza a integração de dados sísmicos de alta resolução, batimétricos, SRTM e imagens de satélite para desenvolvimento da estratigrafia relativa visando entender as variações do nível do mar durante o Quaternário no estuário do rio Apodi-Mossoró e plataforma adjacente, nordeste do Brasi [...] l. A principal feição identificada foi um canal submerso, na plataforma interna, parcialmente preenchido, provavelmente relacionado com o sistema de vales incisos formado durante o rebaixamento do nível do mar no Pleistoceno. O canal apresenta duas direções principais (NW-SE e NE-SW), em forma da letra J, aparentemente controladas pelas estruturas tectônicas da Bacia Potiguar. A margem oeste do canal é relativamente soerguida em relação à margem leste. Com base nos dados sísmicos foi possível identificar uma descontinuidade presente em toda a área, interpretada como o limite Pleistoceno/Holoceno, bem como sismofácies referentes a padrões de preenchimento e sedimentação do canal submerso e da plataforma durante a subida do nível do mar no Holoceno. Abstract in english This study focuses on the Quaternary sea level changes in the Apodi-Mossoró Estuary and adjacent shelf, Northeastern Brazil, based on the analysis of high-resolution seismic profiles, integrated with echosounder, SRTM and satellite image data. We use these data to develop a relative stratigraphy. An [...] incised-valley extending from the Apodi-Mossoró Estuary onto the shelf dominates the investigated area. In very shallow waters (down to 10 m depth) the channel lies mainly in a NW-SE direction, changing to NE-SW in waters below10 m, in the form of a J-shaped valley. The southern flank of the shallow channel presents an abrupt morphology, probably determined by a residual scarp due to neotectonic reactivation of a pre-existing fault. This incised-valley can be correlated with a former river valley formed during the late Pleistocene fall in sea-level. The base-level change related to this drop in sea level can be regionally expressed on seismic lines as a laterally-continuous stratigraphic surface named Horizon I, interpreted as representing the sub-aerial exposure of the continental shelf. Many incised valleys were excavated on this exposed shelf, including that of the Apodi-Mossoró Estuary and its incised valley system. This incised valley has lain buried since the Holocene transgression. The Holocene sediments present sub-horizontal layers, or they have filled the incised valley with oblique features.

Helenice, Vital; Samia F.Lima, Furtado; Moab Praxedes, Gomes.

325

High-frequency propagating density fluctuations in deeply supercooled water: evidence of a single viscous relaxation.  

Science.gov (United States)

We performed a Brillouin scattering experiment on deeply supercooled water and compared the results with similar literature data obtained both at the same and at higher values of the exchanged wave vector. The whole set of available experimental data can be well reproduced with the use of the generalized hydrodynamic model where all the involved thermodynamic parameters are fixed to their literature values. On the contrary, the model based on the memory function approach generates the wrong estimates for measurables when the same values of the thermodynamic parameters are used. This result confirms our recent criticisms against the utilization of models originating from linear response theory [Phys. Rev. E 84, 051202 (2011)]. The inconsistency between models explains apparent discrepancies between the different conclusions on water acoustic behavior which may be found in the literature. We demonstrate that the observed behavior can be explained by assuming only a single relaxation process that is typical of any viscoelastic system. With all thermodynamics quantities fixed, the hydrodynamic description needs only two parameters to model the experimental data, namely, the relaxation time and the high-frequency limit of the sound velocity. The whole body of the experimental data can be well reproduced when the relaxation time behaves in an Arrhenian manner and the difference between the relaxed and not relaxed sound velocities is a constant. The high-frequency sound velocity is never higher than 2200 m/s. We conclude that, at least from experiments performed within the hydrodynamic regime, there is no indication for a fast sound close to the hypersonic velocity observed in ice. PMID:23496512

Aliotta, F; Gapi?ski, J; Pochylski, M; Ponterio, R C; Saija, F; Salvato, G; Vasi, C

2013-02-01

326

Stable isotope fingerprint of open-water evaporation losses and effective drainage area fluctuations in a subarctic shield watershed  

Science.gov (United States)

SummaryStable isotopes of water, oxygen-18 and deuterium, were measured at biweekly to monthly intervals during the open-water season in a small, headwater lake (Pocket Lake, 4.8 ha) near Yellowknife Northwest Territories, and concurrently in a nearby string-of-lakes watershed (Baker Creek, 137 km 2) situated in the subarctic Precambrian Shield region. As measured in water samples collected over a 12 year period (1997-2008), the levels of evaporative isotopic enrichment in both lake and watershed outflow were differentially offset, and seasonal variations were found in both to be driven by variations in open-water evaporation. Systematic differences measured in the magnitude of the offset between the lake and watershed outflow are interpreted as being caused by changes in the effective drainage area contributing to runoff. Based on the observed and extremely consistent relationship between isotopic compositions of lake water and watershed outflow ( r2 = 0.849, p < 0.001) we extend the analysis of open-water evaporation losses and effective drainage areas back to 1991 when less-frequent water sampling at the sites commenced. This 18-year record serves to demonstrate for the first time the expected variability in the evaporation and transpiration partitioning, upper limits on the effective drainage area, and isotopic signals transferred downstream in a typical shield drainage system within the Mackenzie Basin.

Gibson, J. J.; Reid, R.

2010-02-01

327

Ground-water levels in an alluvial plain between the Tanana and Chena Rivers near Fairbanks, Alaska 1986-93  

Science.gov (United States)

The aquifer of an alluvial plain between the Tanana and Chena Rivers near Fairbanks, Alaska, generally consists of highly transmissive sands and gravels under water-table conditions. During 1986-88, the U.S. Geological Survey studied the distribution of ground-water levels in the alluvial plain between Moose Creek Dam and the confluence of the Tanana and Chena Rivers. Moose Creek Dam is a flood-control structure on the Chena River that impounds water only during high flows in the Chena River or during tests of the dam's control gates. Ground-water-level information is needed to help design and place septic systems, buildings, and drainage structures. Using 38 existing wells and 83 wells drilled for this study during 1986 and 1987, ground-water levels were measured to determine the depth to the water table, its seasonal variation, and its relation to changes in river and reservoir stages. Water levels were continuously measured in 10 wells and periodically measured in 110 other wells until August 1988. During 1989, water levels were measured at least once in 59 wells. Three wells were equipped with water-level recorders through 1993. River stages were measured continuously at one gaging station on the Tanana River and at two stations on the Chena River. During summer months of 1986-88, stages and discharges in the Chena River were generally less than long-term mean monthly values, whereas mean monthly stages and discharges in the Tanana River fluctuated above and below long-term mean monthly values. Depths to water in monitoring wells ranged from slightly above land surface to about 21 feet below land surface. Depths to water in the alluvial plain were within 10 feet of land surface in most areas, but were within 5 feet of land surface in many low-lying areas. In general, the water table sloped to the northwest, from the Tanana River to the Chena River, at a gradient of about 4 feet per mile. Water levels in wells within about half a mile of either river responded rapidly to changes in river stage. During summer months of 1989-93, stages and discharges in the Chena River were generally higher than those during 1986-88, whereas stages and discharges in the Tanana River were similar to those during 1986-88. During 1989, peak water levels were higher in more than half the wells measured than during peak levels observed during 1986-88. Peak water levels were also 1.9 to 3.3 feet higher in 1991 or 1992 than peak values during 1986-88 in three wells equipped with water-level recorders. Water levels in wells near Moose Creek Dam responded rapidly to changes in water levels behind the dam. During one impoundment, water levels in a well 0.1 mile from the dam rose approximately 7 feet, to 4.8 feet below land surface.

Glass, R.L.; Lilly, M.R.; Meyer, D.F.

1996-01-01

328

Measurements of wall pressure fluctuations on a cylinder in annular water flow with upstream flow disturbances  

International Nuclear Information System (INIS)

Data for surface pressures on a finite length rod in an annular region with upstream disturbances are presented and related to the existing data for well developed flow. Normalizations of the power spectral densities for different flow rates and three hydraulic diameters are presented, and the possible spurious effects on pressure measurements are discussed. Power spectral density levels are identified which predict the same order of magnitude response as measured in a vibration study, and a general approach for predicting rod response to axially nonhomogeneous pressure fields is outlined. (orig.)

329

Considering rating curve uncertainty in water level predictions  

Science.gov (United States)

Streamflow cannot be measured directly and is typically derived with a rating curve model. Unfortunately, this causes uncertainties in the streamflow data and also influences the calibration of rainfall-runoff models if they are conditioned on such data. However, it is currently unknown to what extent these uncertainties propagate to rainfall-runoff predictions. This study therefore presents a quantitative approach to rigorously consider the impact of the rating curve on the prediction uncertainty of water levels. The uncertainty analysis is performed within a formal Bayesian framework and the contributions of rating curve versus rainfall-runoff model parameters to the total predictive uncertainty are addressed. A major benefit of the approach is its independence from the applied rainfall-runoff model and rating curve. In addition, it only requires already existing hydrometric data. The approach was successfully demonstrated on a small catchment in Poland, where a dedicated monitoring campaign was performed in 2011. The results of our case study indicate that the uncertainty in calibration data derived by the rating curve method may be of the same relevance as rainfall-runoff model parameters themselves. A conceptual limitation of the approach presented is that it is limited to water level predictions. Nevertheless, regarding flood level predictions, the Bayesian framework seems very promising because it (i) enables the modeler to incorporate informal knowledge from easily accessible information and (ii) better assesses the individual error contributions. Especially the latter is important to improve the predictive capability of hydrological models.

Sikorska, A. E.; Scheidegger, A.; Banasik, K.; Rieckermann, J.

2013-11-01

330

Screening Experiments for Removal of Low-Level Tritiated Water  

International Nuclear Information System (INIS)

Screening experiments for low levels of tritiated water (HTO) remediation based upon selective adsorption/desorption mechanisms utilizing equilibrium isotope effects have been carried out. Several organic and inorganic high surface area materials were investigated to assess their ability to selectively adsorb low concentrations of HTO. Ion-exchange resins with cation functionalities, chitosan, sodium alginate, and several inorganic media modified with metal cations exhibited promising results. Biomaterials, for example, chitosan and modified alginate, demonstrated positive results. Based on the literature and our preliminary testing, we postulate four possible mechanisms for selected tritium adsorption: hydrogen ion exchange, HTO coordination with surface cation sites, hydrogen bonding to surface basic sites, and secondary hydrogen bonding (structural water) in fine pores

331

Estimation of the influence of level fluctuations of the Caspian Sea on navigation and development of activities on the improvement of the condition of the infrastructure of waterways in the delta of the Astrakhan region  

Directory of Open Access Journals (Sweden)

Full Text Available According experts’ forecasts, the fall of the level of the Caspian Sea, which has been recently stabilized on the mark – minus 26.5 m. on the coast of the Russian Federation, is expected. The modern condition of waterways of the Astrakhan region is considered due to the fact that navigation belongs to basic branches of the national economy, depending on fluctuations of the sea level. It is noticed that many objects of the infrastructure of the Astrakhan region, such as industrial enterprises, agricultural and fishing organizations, and ports, including the port Olya, are situated in so-called "coastal zone of risk". It is offered to apply bank protection of half-slope type as means to protect the given territo-ries from the influence of waters of the Caspian Sea. It is a levee, which frontal slope is strengthened by precast concrete slabs.

Karasaeva Al’finur Ravil’evna

2010-10-01

332

An Indirect Adaptive Controller to Regulate UTSG Water Level in Pressurized Water Nuclear Reactor  

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Full Text Available Stabilizing water level of the Steam Generator (SG in nuclear power plant is a very important problem since its parameters vary with operating conditions and dynamics of the system is very different according to the power levels and changes as time goes on. Therefore, it is an intractable as well as challenging task to improve the water level control system of the SG. In this study, a new framework for building an adaptive Minimum Variance controller for stabilizing water-level of SG is proposed. We use the recursive least squares algorithm to identify the Input/Output models. Minimum Variance Control (MVC law is also used to develop the adaptation controller. Emphasis is put on the evaluation of the parameter identification in order to avoid instabilities because of disturbances or insufficient excitations. This is especially of importance when the adaptive control is carried out in closed loop systems and without additional test signals. The algorithm so proposed is simulated and applied to the water level control in the U-Tube Steam Generating unit (UTSG used for electricity generation. It is shown through application to a nonlinear model of steam generators that the proposed controller has good performance.

Djamel Boukhetala

2012-01-01

333

The Organochlorine Pesticides Residue Levels in Karun River Water  

Directory of Open Access Journals (Sweden)

Full Text Available Background: The organochlorine pesticides (OCPs are among the most commonly used in water streams around the world. Most of these contaminants are highly hydrophobic and persist in sediments of rivers and lakes. Studies have suggested that OCPs may affect the normal function of the human and wildlife endocrine systems.Objectives: The aim of this study is to determine the concentrations of selected organochlorine pesticides residues [OP'DDT, PP'DDT, alderin, dieldrin, heptachlor, (?,ß,?,? HCH, (?, ß endosulfan and metoxychlor] in samples from Karun River water at Khuzestan province in Iran , by GC-µ-ECD.Materials and Methods: Water was extracted with n-hexane and then purified by passing through a glass column packed with Florisil and Na2SO4, which was then eluted with ether: hexane solution v/v.Results: In general, all of 12 investigated organochlorine pesticides (OCPs were detected. Regardless of the kind of OCPs, the highest OCP pollution level in Karun River were seen from August to November 2009 ranging 71.43 – 89.34 µg/L, and the lowest were seen from Dec 2010 to March 2011 at levels of 22.25 - 22.64 µg/L. The highest and lowest mean concentrations of 12 investigated pesticides were ß-Endosulfan and pp' DDT with 28.51and 0.01 µg/L respectively.Conclusions: Comparison of total organochlorine pesticides residues concentration with WHO guidelines revealed that the Karun River had total OCPs residues above the probable effect level (0.2-20 µg/L, P < 0.05, which could pose a risk to aquatic life.

Behrooz Jannat

2013-01-01

334

Formal specification and animation of a water level monitoring system  

International Nuclear Information System (INIS)

This report describes the Vienna Development Method (VDM), which is a formal method for software specification and development. VDM evolved out of attempts to use mathematics in programming language specifications in order to avoid ambiguities in specifications written in natural language. This report also describes the use of VDM for a real-time application, where it is used to formally specify the requirements of a water level monitoring system. The procedures and techniques used to produce an executable form (animation) of the specification are covered. (Author)

335

Stable carbon and oxygen isotopes reveal Sahel drought events and ground water fluctuations in sub-Saharan Africa  

Science.gov (United States)

Tree rings are important proxies for paleoclimate studies because they contain continuous historical records of inter-annual and intra-annual time resolutions, which range over hundreds of years. This study uses stable carbon and oxygen isotopes in tree rings to understand the drivers and impacts of climate change in sub-Saharan Africa and their ability to reconstruct past regional climate variability and climatic trends. Our approach considers large scale climate gradients and different temporal scales (inter-annual and intra-annual variations) and combines multi- parameter measurements (carbon and oxygen isotopes, whole wood and cellulose measurements). The study species are Faidherbia albida and Sclerocarya birrea from south and West Africa, respectively. Both are very important deciduous trees, and widely distributed in sub-Saharan Africa. Particularly, F. albida has a distinctive phenology; it bears leaves and flowers during the dry season and sheds its leaves during the rainy season. Stable carbon (?13C) and oxygen (?18O) mean values showed similar inter annual patterns. In general, both ?13C and ?18O show negative correlations with rainfall, humidity and PDSI. On the contrary, they are positively correlated with sunshine hours, maximum temperature and evaporation. The reverse phenology of Faidherbia and intra seasonal resolution measurements reveals seasonal ground water fluctuations. Both carbon and oxygen stable isotopes showed strong climatic signals including the long Sahel drought events and climatic recovery phases.

Gebrekirstos, Aster

2014-05-01

336

Design of double-fuzzy-integral intelligent water level controller for steam generator  

International Nuclear Information System (INIS)

In order to effectively control the water level of steam generator, a double-fuzzy-integral water level controller is designed in this paper. A 'false water level' distinguishing fuzzy controller is added before normal fuzzy controller, to control the water level effectively when SG is in 'false water level' phase. In order to have an optimal water level control, this paper gives the result of fuzzy controller and integral controller export in phase. By the analyzing of control curve, it has validated that the designed double-fuzzy-integral water level controller may overcome the disadvantageous influence given by 'false water level' phenomena to the water level control, and that the control excess adjustment quantity is small and the steady time is short. (authors)

337

Detrital input, productivity fluctuations, and water mass circulation in the westernmost Mediterranean Sea since the Last Glacial Maximum  

Science.gov (United States)

By presenting sea surface temperatures, planktonic oxygen isotope profiles, and bulk geochemical composition of core sediments, we offer a multiparameter reconstruction of Western Mediterranean oceanography from the Last Glacial Maximum until the Middle Holocene (20,000-5000 cal years B. P.). Sediments from Ocean Drilling Program Site 975 in the Algero-Balearic basin have been compared with three Alboran basin cores (TTR-300G, TTR-302G, and TTR-304G), all of them investigated at high resolution. This multiproxy approach has allowed two different modes of circulation to be recognized: (1) during the LGM and from ˜8.0 cal. ka B. P. onward, no surface gradient in ?18OG. bulloides is found associated with low productivity, in close analogy to modern conditions; (2) during the Bølling-Allerød and early Holocene, significant surface isotopic gradients are found with periods probably indicating an unstable water column, associated with enhanced productivity and low bottom oxygen conditions. The close synchrony between the occurrence of the surface isotopic offset and organic rich layer formation implicates that the origin of these features is linked, probably via shoaling of the regional thermohaline circulation. Paleo-SSTs, derived from planktonic foraminifer assemblages, indicate abrupt changes in surface conditions during the analyzed time interval. Fluctuations in marine productivity based on Ba and total organic carbon are related to water column stability and atmospheric conditions. A sharp warming and ?18OG. bulloides excursion at the end of the Younger Dryas is probably linked to glacial meltwater influence. The riverine input has been reconstructed using the Mg/Al ratio, and Mg/Al peaks during arid periods (Greenland Stadial-2a and Younger Dryas) related to "bypass" margin processes.

Jimenez-Espejo, F. J.; Martinez-Ruiz, F.; Rogerson, M.; GonzáLez-Donoso, J. M.; Romero, O. E.; Linares, D.; Sakamoto, T.; Gallego-Torres, D.; Rueda Ruiz, J. L.; Ortega-Huertas, M.; Perez Claros, J. A.

2008-11-01

338

High-level radioactive waste from light-water reactors  

International Nuclear Information System (INIS)

The production of radioactive nuclei during the operation of a light-water reactor is traced, and their decay history is followed. The potential environmental impacts of this waste are calculated and shown to be comparable to those of other materials we produce. Assuming deep burial, it is shown that there are important time delays which prevent the waste from reaching the biosphere in the first few hundred years while its toxicity is decreasing by several orders of magnitude. In the long term,,the most important pathway to man was found to be through groundwater into food and water supplies, with consequences calculated t to be 0.4 fatalities in 106 years from each year of all-nuclear power in U.S. Other pathways considered and found to be less important include meteorites, volcanism, release through ground water to airborne particulate, and human intrusion by drilling and mining for unspecified materials and for salt. For time scales longer than 106 years, nuclear power is shown to reduce man's exposure to radiation by consuming uranium. A cost-benefit analysis is developed for surveillance of buried waste. It is shown that buried high-level waste is environmentally much less dangerous than uranium mill tailings

339

CFNN based water level control for nuclear steam generator  

International Nuclear Information System (INIS)

Because normal PID controller can't change its parameters according to the change of control object parameters. In this paper, the compensatory fuzzy neural network (CFNN) was used with a simplified model of nuclear steam generator (NSG) to design a NSG water level controller. Compensatory neurons which were introduced in the CFNN will make the control system improve the quality of fault tolerant and more stable. Meanwhile compensative fuzzy computation is optimized dynamically in the study algorithm of neural network, therefore the network is much more adaptive and the training speed is much faster. The results of simulation show that under this control method the system has smaller maximum overshoot and faster convergence speed than that of under normal PID control method. The CFNN can not only adjust parameters properly on line, but also can optimized relevant fuzzy reasoning in dynamic way, so it suit to be used on ling learning and control. The control method used in this paper is meaningful to the research of NSG water level intelligent control. (authors)

340

Fluctuating water table affects gross ecosystem production and gross radiation use efficiency in a sedge-grass marsh.  

Czech Academy of Sciences Publication Activity Database

Ro?. 692, ?. 1 (2012), s. 57-66. ISSN 0018-8158 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA MŽP(CZ) SP/2D1/93/07; GA MŠk OC08021 Institutional research plan: CEZ:AV0Z60870520 Keywords : Wetland * fen * carbon * water level * Carex acuta L. * Eddy covariance Subject RIV: DA - Hydrology ; Limnology Impact factor: 1.985, year: 2012

Dušek, Ji?í; ?ížková, Hana; Stellner, Stanislav; Czerný, Radek; Kv?t, Jan

2012-01-01

341

Soil water content at the catchment level and plant water status relationships in a Mediterranean Quercus ilex forest  

Science.gov (United States)

SummaryThis paper presents an analysis of the forest hydrology and plant water status interaction, focusing on the relationship between the hydrological water balance at the catchment level and the predawn leaf water potential of the species Quercus ilex (holm oak). The catchment water balance approach was applied to a Mediterranean watershed forested with holm oak to evaluate the daily soil water reserve at the catchment level. After this, evapotranspiration and soil water content were combined to estimate the potential soil water reserve and evaluate plant water status at the catchment level. A close relationship was detected between leaf water potential and the soil water reserve, and was fitted to a negative exponential curve to estimate predawn leaf water potential from a hydrological database. The proposed equation can help to predict the frequency, intensity, and length of droughts potentially capable of causing structural damage to the forest, from the hydrological time series records.

Bellot, J.; Ortiz de Urbina, J. M.

2008-07-01

342

Late Pleistocene and Early Holocene lake-level fluctuations in the Lahontan Basin, Nevada: Implications for the distribution of archaeological sites  

Science.gov (United States)

The Great Basin of the western U.S. contains a rich record of late Pleistocene and Holocene lake-level fluctuations as well as an extensive record of human occupation during the same time frame. We compare spatial-temporal relationships between these records in the Lahontan basin to consider whether lake-level fluctuations across the Pleistocene-Holocene transition controlled distribution of archaeological sites. We use the reasonably well-dated archaeological record from caves and rockshelters as well as results from new pedestrian surveys to investigate this problem. Although lake levels probably reached maximum elevations of about 1230-1235 m in the different subbasins of Lahontan during the Younger Dryas (YD) period, the duration that the lakes occupied the highest levels was brief Paleoindian and early Archaic archaeological sites are concentrated on somewhat lower and slightly younger shorelines (???1220-1225 in) that also date from the Younger Dryas period. This study suggests that Paleoindians often concentrated their activities adjacent to large lakes and wetland resources soon after they first entered the Great Basin. ?? 2008 Wiley Periodicals, Inc.

Adams, K.D.; Goebel, T.; Graf, K.; Smith, G.M.; Camp, A.J.; Briggs, R.W.; Rhode, D.

2008-01-01

343

Water levels in periodically measured wells in the Yucca Mountain Area, Nevada, 1988  

International Nuclear Information System (INIS)

This report presents water-level data for 10 wells that were periodically measured in 1988 in the Yucca Mountain Area, Nevada. Water levels measured during 1987 are included in the report for reference. The report includes discussions of the methods used and corrections applied to obtain water-level depths and altitudes from onsite measurements. Water levels for each well are presented in tabular and graphical (hydrograph) form. The altitude of the water level in the upper part of the saturated zone is about 775 meters above sea level to the west of and along part of the crest of Yucca Mountain; along the eastern edge and southern end of Yucca Mountain, the water level is 728 to 730 meters above sea level. The water-level data were obtained to help evaluate the suitability of the area for storing high-level nuclear waste. 14 refs., 2 figs., 2 tabs

344

Effects of sea-level rise on ground water flow in a coastal aquifer system  

Science.gov (United States)

The effects of sea-level rise on the depth to the fresh water/salt water interface were simulated by using a density-dependent, three-dimensional numerical ground water flow model for a simplified hypothetical fresh water lens that is similar to shallow, coastal aquifers found along the Atlantic coast of the United States. Simulations of sea-level rise of 2.65 mm/year from 1929 to 2050 resulted in an increase in water levels relative to a fixed datum, yet a net decrease in water levels relative to the increased sea-level position. The net decrease in water levels was much greater near a gaining stream than farther from the stream. The difference in the change in water levels is attributed to the dampening effect of the stream on water level changes in response to sea-level rise. In response to the decreased water level altitudes relative to local sea level, the depth to the fresh water/salt water interface decreased. This reduction in the thickness of the fresh water lens varied throughout the aquifer and was greatly affected by proximity to a ground water fed stream and whether the stream was tidally influenced. Away from the stream, the thickness of the fresh water lens decreased by about 2% from 1929 to 2050, whereas the fresh water lens thickness decreased by about 22% to 31% for the same period near the stream, depending on whether the stream was tidally influenced. The difference in the change in the fresh water/salt water interface position is controlled by the difference in the net decline in water levels relative to local sea level. ?? 2007 National Ground Water Association.

Masterson, J.P.; Garabedian, S.P.

2007-01-01

345

Non Invasive Water Level Monitoring on Boiling Water Reactors Using Internal Gamma Radiation: Application of Soft Computing Methods  

International Nuclear Information System (INIS)

To provide best knowledge about safety-related water level values in boiling water reactors (BWR) is essentially for operational regime. For the water level determination hydrostatic level measurement systems are almost exclusively applied, because they stand the test over many decades in conventional and nuclear power plants (NPP). Due to the steam generation especially in BWR a specific phenomenon occurs which leads to a water-steam mixture level in the reactor annular space and reactor plenum. The mixture level is a high transient non-measurable value concerning the hydrostatic water level measuring system and it significantly differs from the measured collapsed water level. In particular, during operational and accidental transient processes like fast negative pressure transients, the monitoring of these water levels is very important. In addition to the hydrostatic water level measurement system a diverse water level measurement system for BWR should be used. A real physical diversity is given by gamma radiation distribution inside and outside the reactor pressure vessel correlating with the water level. The vertical gamma radiation distribution depends on the water level, but it is also a function of the neutron flux and the coolant recirculation pump speed. For the water level monitoring, special algorithms are required. An analytical determination of the gamma radiation distribution outside the reactor pressure vessel is impossible due to the multitude of radiis impossible due to the multitude of radiation of physical processes, complicated non-stationary radiation source distribution and complex geometry of fixtures. For creating suited algorithms Soft Computing methods (Fuzzy Sets Theory, Artificial Neural Networks, etc.) will be used. Therefore, a database containing input values (gamma radiation distribution) and output values (water levels) had to be built. Here, the database was established by experiments (data from BWR and from a test setup) and simulation with the authorised thermo-fluid code ATHLET. (authors)

346

Surface water considerations for low-level radioactive waste site  

International Nuclear Information System (INIS)

To ensure that the objective of isolation of low-level radioactive wastes and stability of the disposal site after closure can be achieved, the surface hydrology of the potential sit must be carefully characterized prior to engineering and operation. At a site the most important considerations with regard to flooding, infiltration, erosion, and pathway of radionuclides are addressed as they relate to streams, ponds, hydraulic structures, and surface water users. To satisfactorily characterize the site, the type and amount of data and analyses needed for license applications and the environmental report are discussed. The discussion also includes potential sources of available data, the field data collection program that may be necessary, and methodologies that can be used for analysis

347

Trend analysis of ground-water levels and spring discharge in the Yucca Mountain Region, Nevada and California, 1960-2000  

Science.gov (United States)

Ground-water level and discharge data from 1960 to 2000 were analyzed for the Yucca Mountain region of southern Nevada and eastern California. Included were water-level data from 37 wells and a fissure (Devils Hole) and discharge data from five springs and from a flowing well. Data were evaluated for variability and for upward, downward, or cyclic trends with an emphasis on the period 1992-2000. Potential factors causing trends in water levels and discharge include ground-water withdrawal, infiltration of precipitation, earthquakes, evapotranspiration, barometric pressure, and earth tides. Statistically significant trends in ground-water levels or spring discharge from 1992 to 2000 were upward at 12 water-level sites and downward at 14 water-level sites and 1 spring-discharge site. In general, the magnitude of the change in water level from 1992 to 2000 was small (less than 2 feet), except where influenced by pumping or local effects such as possible equilibration from well construction or diversion of nearby surface water. Seasonal trends are superimposed on some of the long-term (1992-2000) trends in water levels and discharge. Factors causing seasonal trends include barometric pressure, evapotranspiration, and pumping. The magnitude of seasonal change in water level can vary from as little as 0.05 foot in regional aquifers to greater than 5 feet in monitoring wells near large supply wells in the Amargosa Farms area. Three major episodes of earthquake activity affected water levels in wells in the Yucca Mountain region between 1992 and 2000: the Landers/Little Skull Mountain, Northridge, and Hector Mine earthquakes. The Landers/Little Skull Mountain earthquakes, in June 1992, had the largest observed effect on water levels and on discharge during the study period. Monthly measurements of wells in the study network show that earthquakes affected water levels from a few tenths of a foot to 3.5 feet. In the Ash Meadows area, water levels remained relatively stable from 1992 to 2000, with some water levels showing small rising trends and some declining slightly. Possible reasons for water-level fluctuations at sites AD-6 (Tracer Well 3), AM-5 (Devils Hole Well), and AM-4 (Devils Hole) from 1960 to 2000 include climate change, local and regional ground-water withdrawals, and tectonic activity. In Jackass Flats, water levels from 1992 to 2000 in six wells adjacent to Fortymile Wash displayed either small upward trends or no upward or downward trend. Comparison of trends in water levels from 1983 to 2000 for these six wells shows good correlations between all wells and suggests a common mechanism controlling water levels in the area. Of the likely controls on the system--precipitation or pumping in Jackass Flats--precipitation appears to be the predominant factor controlling water levels near Fortymile Wash. Water levels in the heavily pumped Amargosa Farms area declined from about 10 to 30 feet from 1964 to 2000. Water-level declines accelerated beginning in the early 1990's as pumping rates increased substantially. Pumping in the Amargosa Farms area may affect water levels in some wells as far away as 5-14 miles. The water level at site DV-3 (Travertine Point 1 Well) and discharge at site DV-2 (Navel Spring), both in the Death Valley hydrographic area, had downward trends from 1992 to 2000. The cause of these downward trends may be linked to earthquakes, pumping in the Amargosa Farms area, or both.

Fenelon, Joseph M.; Moreo, Michael T.

2002-01-01

348

Trend Analysis of Ground-Water Levels and Spring Discharge in the Yucca Mountain Region, Nevada and California, 1960-2000  

International Nuclear Information System (INIS)

Ground-water level and discharge data from 1960 to 2000 were analyzed for the Yucca Mountain region of southern Nevada and eastern California. Included were water-level data from 37 wells and a fissure (Devils Hole) and discharge data from five springs and from a flowing well. Data were evaluated for variability and for upward, downward, or cyclic trends with an emphasis on the period 1992-2000. Potential factors causing trends in water levels and discharge include ground-water withdrawal, infiltration of precipitation, earthquakes, evapotranspiration, barometric pressure, and earth tides. Statistically significant trends in ground water levels or spring discharge from 1992 to 2000 were upward at 12 water-level sites and downward at 14 water-level sites and 1 spring-discharge site. In general, the magnitude of the change in water level from 1992 to 2000 was small (less than 2 feet), except where influenced by pumping or local effects such as possible equilibration from well construction or diversion of nearby surface water. Seasonal trends are superimposed on some of the long-term (1992-2000) trends in water levels and discharge. Factors causing seasonal trends include barometric pressure, evapotranspiration, and pumping. The magnitude of seasonal change in water level can vary from as little as 0.05 foot in regional aquifers to greater than 5 feet in monitoring wells near large supply wells in the Amargosa Farms area. Three major episodes of earthquake activity affecajor episodes of earthquake activity affected water levels in wells in the Yucca Mountain region between 1992 and 2000: the Landers/Little Skull Mountain, Northridge, and Hector Mine earthquakes. The Landers/Little Skull Mountain earthquakes, in June 1992, had the largest observed effect on water levels and on discharge during the study period. Monthly measurements of wells in the study network show that earthquakes affected water levels from a few tenths of a foot to 3.5 feet. In the Ash Meadows area, water levels remained relatively stable from 1992 to 2000, with some water levels showing small rising trends and some declining slightly. Possible reasons for water-level fluctuations at sites AD-6 (Tracer Well 3), AM-5 (Devils Hole Well), and AM-4 (Devils Hole) from 1960 to 2000 include climate change, local and regional ground-water withdrawals, and tectonic activity. In Jackass Flats, water levels from 1992 to 2000 in six wells adjacent to Fortymile Wash displayed either small upward trends or no upward or downward trend. Comparison of trends in water levels from 1983 to 2000 for these six wells shows good correlations between all wells and suggests a common mechanism controlling water levels in the area. Of the likely controls on the system-precipitation or pumping in Jackass Flats-precipitation appears to be the predominant factor controlling water levels near Fortymile Wash. Water levels in the heavily pumped Amargosa Farms area declined from about 10 to 30 feet from 1964 to 2000. Water-level declines accelerated beginning in the early 1990's as pumping rates increased substantially. Pumping in the Amargosa Farms area may affect water levels in some wells as far away as 5-14 miles. The water level at site DV-3 (Travertine Point 1 Well) and discharge at site DV-2 (Navel Spring), both in the Death Valley hydrographic area, had downward trends from 1992 to 2000. The cause of these downward trends may be linked to earthquakes, pumping in the Amargosa Farms area, or both

349

Subtidal variability in water levels inside a subtropical estuary  

Science.gov (United States)

Year-long time series of water level are analyzed at five locations along the St. Johns River Estuary, Florida, to investigate propagation of subtidal pulses. Hilbert-transformed Empirical Orthogonal Functions (HEOFs) are obtained after a dominant seasonal signal is extracted from the data. These functions provide information on spatial structure and propagation phase of subtidal water level pulses. The first HEOF mode explains 96% of the subtidal variability and features an unusual spatial structure: amplitude attenuation (averaging 1 mm/km) to 55 km upstream, slight amplification (0.16 mm/km) over the middle 70 km, and attenuation (2.3 mm/km) over the final 18 km of the estuary. The phase suggests a shift from progressive to quasi-standing wave behavior at 55 km from the estuary mouth. Additionally, local minima in the phase suggest two sources of subtidal forcing: the coastal ocean and the upstream end. An analytical model describing the evolution of long waves through a channel with frictional damping is fit to the amplitude of HEOF mode 1. Solutions are obtained as a function of two parameters: the nondimensional length of the basin, ?, and the nondimensional frictional depth, ?. Values of ? between 0.55 and 0.67 and ? between 1.45 and 1.7 provide the best fit with the HEOF results (1% error or less). These values indicate a highly frictional environment in which the average subtidal wavelength is 10 times the basin length. Subtidal pulses in this estuary, therefore, behave as damped waves that can be represented with idealized models.

Henrie, Krista; Valle-Levinson, Arnoldo

2014-11-01

350

Natural radioactivity levels in different mineral waters from Bulgaria  

International Nuclear Information System (INIS)

The total radioactivity content of 76 mineral waters from different districts in Bulgaria was determined. Natural radioactivity levels resulting from uranium, radium-226, gross alpha and gross beta activity were measured. The results show that the specific activity range from < 0.02 Bq/l to 1.34 (12) Bq/l and from 0.068 (23) Bq/l to 2.60 (50) Bq/l for gross alpha and gross beta activity respectively. For natural Uranium the results vary between 0.020 (5) ?g/l and 180(50) ?g/l. Radium-226 content is between < 0.03 Bq/l to 0.296 (75) Bq/l. Due to differences in the geological structure of the aquifer, a large difference in values of the radioactive content was mSv/year. Excluding one value, TID do not exceed the permissible limit of 0.10 mSv/year. The correlations between investigated isotopes and Total Dissolved observed. The estimated Total Indicative Dose (TID) ranged from 0.0113 (57) mSv/year to 0.1713 (481) Solvents (TDS) in water were carried out. The results do not show a strong correlation between TDS values and dissolved radionuclides. (author)

351

Water level measuring method in pipelines of steam generator  

International Nuclear Information System (INIS)

The device of the present invention can accurately and continuously monitor the water level of pipelines on high temperature side (hot legs) of a steam generator upon periodical inspection of a PWR type reactor. Namely, a supersonic wave sensor is disposed on the lower surface of the laterally disposed pipelines such as hot legs, and supersonic waves generated upwardly are reflected to the water surface in the pipeline and received. Then, the time difference between sending and reception is measured by a measuring device. In order to prevent degradation at high temperature and radiation damages of the supersonic wave sensor, the device is structured such that the supersonic sensor is attached and detached easily to and from the pipeline upon start and completion of the periodical inspection. Since the present invention does not require scraping or welding fabrication of pipeline, it can be disposed extremely easily compared with a conventional visual observation method by using a perspective-type small tube or a method by using coolant pressure difference. (I.S.)

352

GPS water level measurements for Indonesia's Tsunami Early Warning System  

Directory of Open Access Journals (Sweden)

Full Text Available On Boxing Day 2004, a severe tsunami was generated by a strong earthquake in Northern Sumatra causing a large number of casualties. At this time, neither an offshore buoy network was in place to measure tsunami waves, nor a system to disseminate tsunami warnings to local governmental entities. Since then, buoys have been developed by Indonesia and Germany, complemented by NOAA's Deep-ocean Assessment and Reporting of Tsunamis (DART buoys, and have been moored offshore Sumatra and Java. The suite of sensors for offshore tsunami detection in Indonesia has been advanced by adding GPS technology for water level measurements.

The usage of GPS buoys in tsunami warning systems is a relatively new approach. The concept of the German Indonesian Tsunami Early Warning System (GITEWS (Rudloff et al., 2009 combines GPS technology and ocean bottom pressure (OBP measurements. Especially for near-field installations where the seismic noise may deteriorate the OBP data, GPS-derived sea level heights provide additional information.

The GPS buoy technology is precise enough to detect medium to large tsunamis of amplitudes larger than 10 cm. The analysis presented here suggests that for about 68% of the time, tsunamis larger than 5 cm may be detectable.

T. Schöne

2011-03-01

353

GPS water level measurements for Indonesia's Tsunami Early Warning System  

Science.gov (United States)

On Boxing Day 2004, a severe tsunami was generated by a strong earthquake in Northern Sumatra causing a large number of casualties. At this time, neither an offshore buoy network was in place to measure tsunami waves, nor a system to disseminate tsunami warnings to local governmental entities. Since then, buoys have been developed by Indonesia and Germany, complemented by NOAA's Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys, and have been moored offshore Sumatra and Java. The suite of sensors for offshore tsunami detection in Indonesia has been advanced by adding GPS technology for water level measurements. The usage of GPS buoys in tsunami warning systems is a relatively new approach. The concept of the German Indonesian Tsunami Early Warning System (GITEWS) (Rudloff et al., 2009) combines GPS technology and ocean bottom pressure (OBP) measurements. Especially for near-field installations where the seismic noise may deteriorate the OBP data, GPS-derived sea level heights provide additional information. The GPS buoy technology is precise enough to detect medium to large tsunamis of amplitudes larger than 10 cm. The analysis presented here suggests that for about 68% of the time, tsunamis larger than 5 cm may be detectable.

Schöne, T.; Pandoe, W.; Mudita, I.; Roemer, S.; Illigner, J.; Zech, C.; Galas, R.

2011-03-01

354

Effects of alternative Missouri River management plans on ground-water levels in the lower Missouri River flood plain  

Science.gov (United States)

In 1998, the U.S. Army Corps of Engineers (USACE) proposed eight Alternative River Management Plans (ARMPs) for managing reservoir levels and water-release rates for the Missouri River. The plans include the Current Water Control Plan (CWCP), Conservation 18, 31, and 44 (C18, C31, and C44) that provide different levels of water conservation in the reservoirs during droughts, Fish and Wildlife 10, 15, and 20 (FW10, FW15, and FW20) that vary water-release rates to provide additional fish and wildlife benefits, and Mississippi River 66 (M66) that maintains a 66,000 cubic feet per second discharge at St. Louis to provide navigation support for the Mississippi River. Releases from Gavin?s Point Dam affect both the lower 1,305 kilometers of the Missouri River and ground-water levels in the lower Missouri River flood plain. Changes in the magnitude and timing of ground-water-level fluctuations in response to changes in river management could impact agriculture, urban development, and wetland hydrology along the lower Missouri River flood plain. This study compared simulated ground-water altitude and depth to ground water for the CWCP in the Missouri River alluvial aquifer near the Kansas City area between 1970 and 1980 with each ARMP, determined the average change in simulated ground-water level for selected river-stage flood pulses at selected distances from the river, and compared simulated flood pulse, ground-water responses with actual flood pulse, and ground-water responses measured in wells located at three sites along the lower Missouri River flood plain.For the model area, the percent total shallow ground-water area (depth to ground water less than 0.3048 meter) is similar for each ARMP because of overall similarities in river flow between ARMPs. The percent total shallow ground-water area for C18 is the most similar to CWCP followed by C31, M66, C44, FW10, FW15, and FW20. ARMPs C18, C31, C44, and M66 do not cause large changes in the percent shallow ground-water area when compared to CWCP. FW10 and FW15 each cause a spring increase and a summer decrease in the shallow ground-water area. FW20 has a larger spring increase in the shallow ground-water area, but the largest decrease is delayed into November. Analysis of daily changes between the ARMPs indicate large differences can exist in both duration and extent of shallow ground-water areas.A series of 12 flood pulses of 0.5-, 1-, and 3-meters in magnitude and 1-, 8-, 32-, and 128-days in duration were simulated using the ground-water flow model. A ground-water response factor (GWRF, defined as the change in ground-water level at a known distance from the river, at a specified time after the beginning of a flood pulse divided by the magnitude of the flood pulse) was determined daily for selected distances from the river. The GWRF multiplied by the magnitude of the flood pulse can be used to estimate the change in ground-water level at a known time after the beginning of a flood pulse for a known distance from the river. Flood-pulse simulation results indicate the relatively small impact on ground-water levels of small river-stage fluctuations of short duration as might occur daily or weekly. The larger impact on ground-water levels from larger river-stage increases of longer duration indicate the importance of river management flow releases, seasonal changes in river flow, and the effects of continuous high-river stage for long periods on ground-water levels of the lower Missouri River flood plain.A comparison of model results to well hydrographs from three areas along the lower Missouri River flood plain was used to determine how closely the simulated GWRFs matched the measured GWRFs for similar flood pulses and the transferability of GWRFs to other parts of the lower Missouri River flood plain. The comparison between the measured and simulated ground-water responses indicate that the simulated ground-water responses can provide a reasonable estimate of the ground-water resp

Kelly, Brian P.

2000-01-01

355

Water levels in wells J-11 and J-12, 1989-91, Yucca Mountain Area, Nevada  

International Nuclear Information System (INIS)

Water levels have been measured in the Yucca Mountain area, Nevada, since 1981 in order to gain a better understanding of the ground-water flow system in the area. Water levels in wells J-11 and J-12 have been periodically measured using calibrated reeled steel tapes since 1989, however, calculation of water-level altitude was not possible prior to 1993 due to missing reference elevations. These elevations were determined in 1993 by the U.S. Geological Survey. During 1989-91, water-level altitudes for well J-11 ranged from 732.09 to 732.40 meters and the mean water-level altitude was 732.19 meters. During 1989-91, water-level altitudes for well J-12 ranged from 727.84 to 728.03 meters, and the mean water-level altitude was 727.95 meters

356

Drinking cholera : salinity levels and palatability of drinking water in coastal Bangladesh  

DEFF Research Database (Denmark)

OBJECTIVES: To measure the salinity levels of common water sources in coastal Bangladesh and explore perceptions of water palatability among the local population to investigate the plausibility of linking cholera outbreaks in Bangladesh with ingestion of saline-rich cholera-infected river water. METHODS: Hundred participants took part in a taste-testing experiment of water with varying levels of salinity. Salinity measurements were taken of both drinking and non-drinking water sources. Informal group discussions were conducted to gain an in-depth understanding of water sources and water uses. RESULTS: Salinity levels of non-drinking water sources suggest that the conditions for Vibrio cholerae survival exist 7-8 days within the local aquatic environment. However, 96% of participants in the taste-testing experiment reported that they would never drink water with salinity levels that would be conducive to V. cholerae survival. Furthermore, salinity levels of participant's drinking water sources were all well below the levels required for optimal survival of V. cholerae. Respondents explained that they preferred less salty and more aesthetically pleasing drinking water. CONCLUSION: Theoretically, V. cholerae can survive in the river systems in Bangladesh; however, water sources which have been contaminated with river water are avoided as potential drinking water sources. Furthermore, there are no physical connecting points between the river system and drinking water sources among the study population, indicating that the primary driver for cholera cases in Bangladesh is likely not through the contamination of saline-rich river water into drinking water sources.

Grant, Stephen Lawrence; Tamason, Charlotte Crim

2015-01-01

357

Drinking cholera : Salinity levels and palatability of drinking water in coastal Bangladesh  

DEFF Research Database (Denmark)

Objectives: To measure the salinity levels of common water sources in coastal Bangladesh and explore perceptions of water palatability among the local population to investigate the plausibility of linking cholera outbreaks in Bangladesh with ingestion of saline-rich cholera-infected river water. Methods: Hundred participants took part in a taste-testing experiment of water with varying levels of salinity. Salinity measurements were taken of both drinking and non-drinking water sources. Informal group discussions were conducted to gain an in-depth understanding of water sources and water uses. Results: Salinity levels of non-drinking water sources suggest that the conditions for Vibrio cholerae survival exist 7-8 days within the local aquatic environment. However, 96% of participants in the taste-testing experiment reported that they would never drink water with salinity levels that would be conducive to V. cholerae survival. Furthermore, salinity levels of participant's drinking water sources were all well below the levels required for optimal survival of V. cholerae. Respondents explained that they preferred less salty and more aesthetically pleasing drinking water. Conclusion: Theoretically, V. cholerae can survive in the river systems in Bangladesh; however, water sources which have been contaminated with river water are avoided as potential drinking water sources. Furthermore, there are no physical connecting points between the river system and drinking water sources among the study population, indicating that the primary driver for cholera cases in Bangladesh is likely not through the contamination of saline-rich river water into drinking water sources.

Grant, Stephen Lawrence; Tamason, Charlotte Crim

2015-01-01

358

Holocene palaeoclimate and sea level fluctuation recorded from the coastal Barker Swamp, Rottnest Island, south-western Western Australia  

Science.gov (United States)

The Holocene palaeoclimatic history of south-western Western Australia (SWWA) has received little attention compared to south-eastern Australia, and this has resulted in conflicting views over the impact of climate variability in the region. We present here a well-dated, high-resolution record from two overlapping sediment cores obtained from the centre of Barker Swamp, Rottnest Island, offshore Perth. The records span the last 8.7 ka, with the main lacustrine phase occurring after 7.4 ka. This site preserves both pollen and several ostracod taxa. The pollen record suggests a long-term shift from the early-mid Holocene to the late Holocene to drier conditions with less shrubland and more low-ground cover and less fire activity. A salinity transfer function was developed from ostracod faunal assemblage data and trace metal ratios (Mg/Ca, Sr/Ca and Na/Ca) and stable isotopes (?18O and ?13C) analysed on selected ostracod valves. These provide a detailed history of evaporation/precipitation (E/P) differences that clearly shows that the SWWA region was subjected to significant climatic shifts over the last 7.4 ka, with a broad shift towards increased aridity after 5 ka. The swamp ranged from fresh to saline as recorded in the ostracod valve chemistry and the independently-derived salinity transfer function. The ostracod record also indicates that a sea-level highstand occurred between ca. 4.5 and 4.3 ka, with probable step-wise increases at 6.75, 6.2, and 5.6 ka, with the last vestiges of salt water intrusion at ca. 1 ka. After about 2.3 ka, the fresh, groundwater lens that underlies the western portion of the island intersected the swamp depression, influencing the hydrology of the swamp. The broad climatic changes recorded in Barker Swamp are also compared with data from southern South Africa, and it is suggested that the Southern Annular Mode appears to have been the dominant driver in the climate of these regions and that the Indian Ocean Dipole is of little importance in the southern regions of the south-western Cape of Africa and south-western Western Australia.

Gouramanis, C.; Dodson, J.; Wilkins, D.; De Deckker, P.; Chase, B. M.

2012-10-01

359

ERPWS: An Energy Efficient Routing Protocol for Conductive Sensor based Water Level Monitoring and Control System using Zigbee and 74HC14 Inverter  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper we have shown how to use conductive sensor, Zigbee and 74HC14 Inverter to monitor the water level and to control the working of pump. This project is designed to automatically fill the over head tank when it gets empty and monitor the water level in it. The motor is switched ON when the water level in the overhead tank drops below a pre fixed low level (on point and puts off the motor when water level rises up to pre fixed high level (off point.The motor is also switched off during the following conditions: when the sump water is exhausted before filling overhead tank, pump running dry, mains voltage fluctuations. We also introduce an energy efficient routing protocol for Wireless Sensor Networks (ERPWS for Conductive Sensor based Water Level Monitoring and Control System using Zigbee (XBEE 802.15.4 in terms of energy consumptions, the packet loss ratio, network lifetime and the average delivery delay. The XBEE used here is XBEE Pro Series 1(XBP24-AWI-001 and IC used is 74HC14 Hex Inverting Schmitt trigger. Simulation results have been obtained by using NS2 simulator. The evaluation results show that the energy consumption of routing using ERPWS is significantly lower than LEACH and traditional routing protocols.

Saima Maqbool

2013-07-01

360

Does Exposure to Nitrate in Drinking Water Contribute Anything the Effect of Water Chlorination on Children Methemoglobin Levels?  

Directory of Open Access Journals (Sweden)

Full Text Available Previous studies showed contradictory findings regarding the relationship between nitrate in drinking well-water and abnormal methemoglobin (MetHb level (>2% among children. We studied the effect of water chlorination in this relationship in children aged up to 7. 240 subclinical children participated in this cross-sectional study. Water nitrate was analyzed for each participant, and so was blood MetHb. Analysis of two water nitrate exposure levels (50 mg/L as -other extraneous factors (Breslow-Day-Test for interaction, bivariate and multivariate analyses were performed. Abnormal MetHb levels (up to 7.9% were associated (p-value = 0.020 with exposure to drinking water nitrate. Only water chlorination was an effect modifier. Among those who do not disinfect water, the prevalence of ab- normal MetHb for those with nitrate level >50 mg/L was 4.95 (p-value = 0.001, 95% CI = [1.92 - 12.79] times the prevalence for those with nitrate level <50 mg/L. Whereas, among those who do disinfect water, the prevalence for those with high nitrate levels was only 1.38 (p-value = 0.435, 95% CI = [0.62 - 3.07] times the prevalence of those with low nitrate levels. The biological plausibility of a relationship between waterborne microorganisms, drinking water nitrate, drinking water chlorination, and development of an abnormal MetHb level needs to be further explored.

Rajae ElAouad

2012-02-01

361

An oxidative fluctuation hypothesis of aging generated by imaging H2O2 levels in live Caenorhabditis elegans with altered lifespans.  

Science.gov (United States)

Reactive oxygen species (ROS) are important factors mediating aging according to the free radical theory of aging. Few studies have systematically measured ROS levels in relationship to aging, partly due to the lack of tools for detection of specific ROS in live animals. By using the H2O2-specific fluorescence probe Peroxy Orange 1, we assayed the H2O2 levels of live Caenorhabditis elegans with 41 aging-related genes being individually knocked down by RNAi. Knockdown of 14 genes extends the lifespan but increases H2O2 level or shortens the lifespan but decreases H2O2 level, contradicting the free radical theory of aging. Strikingly, a significant inverse correlation between lifespan and the normalized standard deviation of H2O2 levels was observed (p < 0.0001). Such inverse correlation was also observed in worms cultured under heat shock conditions. An oxidative fluctuation hypothesis of aging is thus proposed and suggests that the ability of animals to homeostatically maintain the ROS levels within a narrow range is more important for lifespan extension than just minimizing the ROS levels though the latter still being crucial. PMID:25701790

Fu, Xinmiao; Tang, Yan; Dickinson, Bryan C; Chang, Christopher J; Chang, Zengyi

2015-03-20

362

Water levels in periodically measured wells in the Yucca Mountain area, Nevada, 1981--1987  

International Nuclear Information System (INIS)

This report presents water-level data for 28 wells that have been periodically measured in the Yucca Mountain area, Nevada. The report includes discussions of the methods used and corrections applied to obtain water-level depths and altitudes from onsite measurements. Water levels for each well are presented in tabular and graphical (hydrograph) form. The altitude of the water level in the upper part of the saturated zone is about 775 meters above sea level to the west of and along part of the crest of Yucca Mountain; along the eastern edge and southern end of Yucca Mountain, the water level is nearly horizontal and is 728 to 730 meters above sea level. The water-level data were obtained in cooperation with the US Department of Energy to help evaluate the suitability of the area for storing high-level nuclear waste. 38 refs., 3 figs., 2 tabs

363

Effect of underground water level on electron orbit at SPring-8 storage ring  

International Nuclear Information System (INIS)

We studied the effect of underground water level on electron orbit. A hole was drilled in a rock on which the SPring-8 storage ring was built. Water level in the hole was measured, and the relation between the water level and the orbit change was investigated. Close relation between them was found. We studied the mechanism of orbit change due to underground water. From the orbit change distribution around the ring and the floor level change obtained by hydrostatic leveling system, we concluded that the orbit change is caused by floor rise brought by underground water. (author)

364

To save water or not? : A study of water scarcity at multiple levels, and people's attitudestowards it in Bangalore, India  

OpenAIRE

In a situation where population growth and development is to be sustained throughnaturally limited water resources, something needs to be done to either render waterusage more effective or make more water available. This is the situation in Bangalore Urban District (BUD), an ever growing city lying far from perennial water sources. This thesis presents the water situation in BUD, and aims to analyze the current status of water resources on multiple levels in BUD. Further the aim is to look at...

Bogna?s, De?sire?e

2011-01-01

365

Measurements of wall pressure fluctuations on a cylinder in annular water flow with upstream disturbance. Part II. Flow spoilers  

International Nuclear Information System (INIS)

The second part of an experimental study of wall-pressure fluctuations on a circular rod concentrically located in circular channels of three different hydraulic diameters is reported. Part I presented results with no upstream disturbances; this report is concerned with the effects of upstream flow spoilers. Experimental results from the measurement of fluctuating wall pressures are presented in various statistical forms, including power spectral density representations and mean-square values, as the basis for studying the effects of upstream disturbances and hydraulic diameter. The upstream disturbance generated by a grid-type spoiler is shown to have a more dominant effect on wall-pressure fluctuations than the other types of spoilers tested

366

Off-calibration effects on boiling water reactor water level instruments that tap into jet pump diffusers  

International Nuclear Information System (INIS)

A number of water level instruments are included in boiling water reactor (BWR) plant design. These instruments measure reactor pressure vessel (RPV) water level by measuring the differential pressure (DP) between a fixed-height water column (the reference leg) and the RPV (the variable leg) and converting the DP to a height of water. Thus, plant conditions that affect the DP without changing actual water level will affect the indicated water level monitored by the operator in the control room. These conditions include reactor pressure and drywell and reactor building temperatures near the instrument lines as they affect fluid densities and measured pressures in the reference and variable legs. The fuel zone water level instruments are unique in that their variable legs tap into jet pump diffusers. Therefore, these instruments are also affected by flow past the jet pump taps and jet pump developed head. The purpose of the study is to provide a method to determine actual water level using fuel zone water level instruments for various transient and accident conditions. The concept of developing a simple correction as function of jet pump flow became more complicated as the investigation progressed. The present course of action is to (1) continue the development of jet pump flow-related calibration curves that would be used to determine actual water level under off-normal conditions; and (2) evaluate relocation of the fuel zone water level instrument variable leg tap to ater level instrument variable leg tap to a place where the effects of jet pump flow are minimized