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Sample records for surge flow irrigation

  1. Field assessment of surge and continuous furrow irrigation methods in relation to tillage systems

    Science.gov (United States)

    Mattar, Mohamed A.; El-Saadawy, Mohamed A.; Helmy, Mamdouh A.; Sorour, Hussien M.

    2017-04-01

    Surge flow irrigation is one of the irrigation techniques for controlling furrow irrigation. The aim of this study was to investigate the effect of surge furrow irrigation on water management compared with continuous irrigation for different tillage systems. An experimental field was treated with various tillage systems (mouldboard plough, chisel plough and rotary plough) and water irrigation application methods (continuous flow, control) in which irrigation water was applied continuously, and surge flow (3-surges, 4-surges and 5-surges) in which irrigation water was applied intermittently until it reached the tail end of the furrow. The results showed that water savings obtained using the surge technique were 18.58, 11.84 and 18.93% lower water use than with continuous flow, for the mouldboard, chisel and rotary ploughs, respectively. The 3-surges treatment with the rotary plough reduced the advance time by 25.36% from that for continuous irrigation. The 4-surges treatment with the mouldboard plough had the highest water application efficiency (88.13%). The 3-surges treatment with the rotary plough had the highest distribution uniformity (85.01%). The rotary plough did not cause as much soil aeration around the root system as the other tillage systems. The field research provided information about surge flow, aimed at reducing advance times and increasing irrigation efficiency.

  2. 波涌流灌在山东引黄灌区冬小麦机井灌中的应用%Experimental Research on Surge Irrigation Applied to Well Irrigation of Winter Wheat in Yellow River Irrigation Area of Shandong Province

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    This test used the original pumped well irrigation facilities to irrigate the border check of general specification (3 m × 95 m) with surge irrigation system in Yellow River irrigation area of Shandong Province .And we compared the surge irrigation water flow propulsion ,change of soil water content and water use efficiency of winter wheat with continuous irrigation .Under the test condi‐tion ,the results showed that the second period of surge irrigation which had two periods and whose water-saving rate was 10% was 1 .85~1 .88 times the average speed of continuous irrigation .And the second period's water propulsion length after watering was 1 .50~1 .71 times that of continuous irrigation .These proved that surge irrigation finished the irrigation task with high quality .At the same time ,the water use efficiency of winter wheat increased by 10 .41% .%试验利用山东引黄灌区内原有机井灌溉设施,在灌区生产较普遍规格(3m×95m)畦田内进行波涌流灌溉,并在水流推进、土壤含水率变化、冬小麦水分利用效率方面与连续灌溉进行了对比。试验条件下研究结果表明,周期数为2,节水率为10%的波涌流灌第二周期平均水流推进速度为连续灌溉的1.85~1.88倍,波涌流灌第二周期停水后的冲长为连续灌停水后的1.50~1.71倍,可以高质量完成灌溉任务,并且冬小麦水分利用效率提高10.41%。

  3. Dependence between sea surge, river flow and precipitation in south and west Britain

    Directory of Open Access Journals (Sweden)

    C. Svensson

    2004-01-01

    Full Text Available Estuaries around Great Britain may be at heightened risk of flooding because of the simultaneous occurrence of extreme sea surge and river flow, both of which may be caused by mid-latitude cyclones. A measure especially suited for extremes was employed to estimate dependence between river flow and sea surge. To assist in the interpretation of why flow-surge dependence occurs in some areas and not in others, the dependence between precipitation and surge and between precipitation and river flow was also studied. Case studies of the meteorological situations leading to high surges and/or river flows were also carried out. The present study concerns catchments draining to the south and west coasts of Great Britain. Statistically significant dependence between river flow and daily maximum sea surge may be found at catchments spread along most of this coastline. However, higher dependence is generally found in catchments in hilly areas with a southerly to westerly aspect. Here, precipitation in south-westerly airflow, which is generally the quadrant of prevailing winds, will be enhanced orographically as the first higher ground is encountered. The sloping catchments may respond quickly to the abundant rainfall and the flow peak may arrive in the estuary on the same day as a large sea surge is produced by the winds and low atmospheric pressure associated with the cyclone. There are three regions where flow-surge dependence is strong: the western part of the English south coast, southern Wales and around the Solway Firth. To reduce the influence of tide-surge interaction on the dependence analysis, the dependence between river flow and daily maximum surge occurring at high tide was estimated. The general pattern of areas with higher dependence is similar to that using the daily maximum surge. The dependence between river flow and daily maximum sea surge is often strongest when surge and flow occur on the same day. The west coast from Wales and

  4. Modeling the thermally governed transient flow surges in multitube condensing flow systems with thermal and flow distribution asymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Wedekind, G.L.; Bhatt, B.L. (Oakland Univ., Rochester, MI (United States))

    1989-08-01

    In a tube-type condenser involving complete condensation, small changes in the inlet vapor flow rate momentarily cause very large transient surges in the outlet liquid flow rate. An equivalent single-tube model is proposed that predicts these transient flow surges for a multitube system. The model, based upon a system mean void fraction model developed earlier, includes the effects of thermal and flow distribution asymmetry associated with each individual condenser tube in the multitube system. Theoretical and experimental verification for a two-tube system is presented.

  5. Runoff-generated debris flows: observations and modeling of surge initiation, magnitude, and frequency

    Science.gov (United States)

    Kean, Jason W.; McCoy, Scott W.; Tucker, Gregory E.; Staley, Dennis M.; Coe, Jeffrey A.

    2013-01-01

    Runoff during intense rainstorms plays a major role in generating debris flows in many alpine areas and burned steeplands. Yet compared to debris flow initiation from shallow landslides, the mechanics by which runoff generates a debris flow are less understood. To better understand debris flow initiation by surface water runoff, we monitored flow stage and rainfall associated with debris flows in the headwaters of two small catchments: a bedrock-dominated alpine basin in central Colorado (0.06 km2) and a recently burned area in southern California (0.01 km2). We also obtained video footage of debris flow initiation and flow dynamics from three cameras at the Colorado site. Stage observations at both sites display distinct patterns in debris flow surge characteristics relative to rainfall intensity (I). We observe small, quasiperiodic surges at low I; large, quasiperiodic surges at intermediate I; and a single large surge followed by small-amplitude fluctuations about a more steady high flow at high I. Video observations of surge formation lead us to the hypothesis that these flow patterns are controlled by upstream variations in channel slope, in which low-gradient sections act as “sediment capacitors,” temporarily storing incoming bed load transported by water flow and periodically releasing the accumulated sediment as a debris flow surge. To explore this hypothesis, we develop a simple one-dimensional morphodynamic model of a sediment capacitor that consists of a system of coupled equations for water flow, bed load transport, slope stability, and mass flow. This model reproduces the essential patterns in surge magnitude and frequency with rainfall intensity observed at the two field sites and provides a new framework for predicting the runoff threshold for debris flow initiation in a burned or alpine setting.

  6. 3D Simulations of a Pyroclastic Surge as an Example of a Compressible Suspension Flow

    National Research Council Canada - National Science Library

    ISHIMINE, Yasuhiro

    2004-01-01

    .... As a conspicuous example of such a flow, we present three-dimensional numerical simulations of a pyroclastic surge, which spreads laterally over the ground surface during some volcanic eruptions...

  7. Countercurrent Air-Water Flow in a Scale-Down Model of a Pressurizer Surge Line

    Directory of Open Access Journals (Sweden)

    Takashi Futatsugi

    2012-01-01

    Full Text Available Steam generated in a reactor core and water condensed in a pressurizer form a countercurrent flow in a surge line between a hot leg and the pressurizer during reflux cooling. Characteristics of countercurrent flow limitation (CCFL in a 1/10-scale model of the surge line were measured using air and water at atmospheric pressure and room temperature. The experimental results show that CCFL takes place at three different locations, that is, at the upper junction, in the surge line, and at the lower junction, and its characteristics are governed by the most dominating flow limitation among the three. Effects of inclination angle and elbows of the surge line on CCFL characteristics were also investigated experimentally. The effects of inclination angle on CCFL depend on the flow direction, that is, the effect is large for the nearly horizontal flow and small for the vertical flow at the upper junction. The presence of elbows increases the flow limitation in the surge line, whereas the flow limitations at the upper and lower junctions do not depend on the presence of elbows.

  8. Numerical study of flow fluctuation attenuation performance of a surge tank

    Institute of Scientific and Technical Information of China (English)

    郭兰兰; 刘正刚; 耿介; 李东; 杜广生

    2013-01-01

    The surge tank plays an important role in ensuring the stability of a water flow standard device. To study the influence of the structure and the working conditions on the regulator performance of a surge tank, a three-dimensional model, including a surge tank, the pipeline and the water tank is built, and the VOF model in the Fluent software is used to simulate the two-phase pulsatile flow in the surge tank. The inlet flow pulsation is defined by the User Defined Functions (UDF), and the outlet flow is set to be a free jet. By calculating the flow fluctuation coefficient of the variation under different flow conditions, the influences of the pulse frequency, the initial water level height and the baffle plate structure on the flow stability are analyzed. It is shown that the surge tank has a good attenuation effect on high-frequency pulsations, there is an optimal initial water level to suppress the fluctuations, the round holes of the baffle should ensure a certain circulation area with the bore diameter small enough to have the necessary damping effect.

  9. Numerical simulation of cavitation surge and vortical flows in a diffuser with swirling flow

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Bin; Wang, Jiong; Xiao, L. Z.; Long, X. [Wuhan University, Hubei (China); Luo, X. [Tsinghua University, Beijing (China); Miyagawa, K. [Waseda University, Tokyo (Japan); Tsujimoto, Yoshinobu [Osaka University, Osaka (Japan)

    2016-06-15

    The strong swirling flow at the exit of the runner of a Francis turbine at part load causes flow instabilities and cavitation surges in the draft tube, deteriorating the performance of the hydraulic power system. The unsteady cavitating turbulent flow in the draft tube is simplified and modeled by a diffuser with swirling flow using the Scale-adaptive simulation method. Unsteady characteristics of the vortex rope structure and the underlying mechanisms for the interactions between the cavitation and the vortices are both revealed. The generation and evolution of the vortex rope structures are demonstrated with the help of the iso-surfaces of the vapor volume fraction and the Qcriterion. Analysis based on the vorticity transport equation suggests that the vortex dilatation term is much larger along the cavity interface in the diffuser inlet and modifies the vorticity field in regions with high density and pressure gradients. The present work is validated by comparing two types of cavitation surges observed experimentally in the literature with further interpretations based on simulations.

  10. Modeling Flood Inundation Induced by River Flow and Storm Surges over a River Basin

    Directory of Open Access Journals (Sweden)

    Wei-Bo Chen

    2014-10-01

    Full Text Available Low-lying coastal regions and their populations are at risk during storm surge events and high freshwater discharges from upriver. An integrated storm surge and flood inundation modeling system was used to simulate storm surge and inundation in the Tsengwen River basin and the adjacent coastal area in southern Taiwan. A three-dimensional hydrodynamic model with an unstructured grid was used, which was driven by the tidal elevation at the open boundaries and freshwater discharge at the upriver boundary. The model was validated against the observed water levels for three typhoon events. The simulation results for the model were in reasonable agreement with the observational data. The model was then applied to investigate the effects of a storm surge, freshwater discharge, and a storm surge combined with freshwater discharge during an extreme typhoon event. The super Typhoon Haiyan (2013 was artificially shifted to hit Taiwan: the modeling results showed that the inundation area and depth would cause severe overbank flow and coastal flooding for a 200 year return period flow. A high-resolution grid model is essential for the accurate simulation of storm surges and inundation.

  11. Comparison of drip, pipe and surge spring root irrigation for Jujube (Ziziphus jujuba Mill. fruit quality in the Loess plateau of China.

    Directory of Open Access Journals (Sweden)

    Qing-Han Gao

    Full Text Available Loess Plateau is a typical rain-fed farming region, facing the threat of drought. Irrigation method is among the most important factors affecting jujube quality. This study investigated the response of Ziziphus jujuba Mill. cv. Lizao quality to three different irrigation methods (drip-, pipe- and surge spring root irrigation combining two water levels (20 m(3/hm(2 and 120 m(3/hm(2. The effects of the trials were evaluated by taking into account the physical-chemical characteristics of jujubes and the antioxidant activity. Concomitant to this, the concentration of some taste-related (viz. glucose, fructose, TSS and malic acid and health-related compounds/parameters (viz. catechin and epicatechin were generally much greater in jujube fruit treated with drip irrigation (120 m(3/hm(2. Different irrigation treatments had no significant effects on antioxidant capacity, total phenolics and proanthocyanidins (except for pipe irrigation 20 m(3/hm(2. The best compromise between quality and irrigation of jujube fruit was achieved with drip irrigation (120 m(3/hm(2.

  12. Mobility of pyroclastic flows and surges at the Soufriere Hills Volcano, Montserrat

    Science.gov (United States)

    Calder, E.S.; Cole, P.D.; Dade, W.B.; Druitt, T.H.; Hoblitt, R.P.; Huppert, H.E.; Ritchie, L.; Sparks, R.S.J.; Young, S.R.

    1999-01-01

    The Soufriere Hills Volcano on Montserrat has produced avalanche-like pyroclastic flows formed by collapse of the unstable lava dome or explosive activity. Pyroclastic flows associated with dome collapse generate overlying dilute surges which detach from and travel beyond their parent flows. The largest surges partially transform by rapid sedimentation into dense secondary pyroclastic flows that pose significant hazards to distal areas. Different kinds of pyroclastic density currents display contrasting mobilities indicated by ratios of total height of fall H, run-out distance L, area inundated A and volume transported V. Dome-collapse flow mobilities (characterised by either L/H or A/V 2/3) resemble those of terrestrial and extraterrestrial cold-rockfalls (Dade and Huppert, 1998). In contrast, fountain-fed pumice flows and fine-grained, secondary pyroclastic flows travel slower but, for comparable initial volumes and heights, can inundate greater areas.

  13. An experimental description of the flow in a centrifugal compressor from alternate stall to surge

    Science.gov (United States)

    Moënne-Loccoz, V.; Trébinjac, I.; Benichou, E.; Goguey, S.; Paoletti, B.; Laucher, P.

    2017-08-01

    The present paper gives the experimental results obtained in a centrifugal compressor stage designed and built by SAFRAN Helicopter Engines. The compressor is composed of inlet guide vanes, a backswept splittered unshrouded impeller, a splittered vaned radial diffuser and axial outlet guide vanes. Previous numerical simulations revealed a particular S-shape pressure rise characteristic at partial rotation speed and predicted an alternate flow pattern in the vaned radial diffuser at low mass flow rate. This alternate flow pattern involves two adjacent vane passages. One passage exhibits very low momentum and a low pressure recovery, whereas the adjacent passage has very high momentum in the passage inlet and diffuses efficiently. Experimental measurements confirm the S-shape of the pressure rise characteristic even if the stability limit experimentally occurs at higher mass flow than numerically predicted. At low mass flow the alternate stall pattern is confirmed thanks to the data obtained by high-frequency pressure sensors. As the compressor is throttled the path to instability has been registered and a first scenario of the surge inception is given. The compressor first experiences a steady alternate stall in the diffuser. As the mass flow decreases, the alternate stall amplifies and triggers the mild surge in the vaned diffuser. An unsteady behavior results from the interaction of the alternate stall and the mild surge. Finally, when the pressure gradient becomes too strong, the alternate stall blows away and the compressor enters into deep surge.

  14. International fund flows: surges, sudden stops, and cyclicality

    NARCIS (Netherlands)

    Li, Suxiao

    2017-01-01

    International fund flows are cross-border investments in domestic equity and bond markets by global investment funds. They have increased dramatically since the 1990s and played an increasingly important role in the transmission of shocks. In this thesis, we examine the drivers of large changes in

  15. International fund flows: surges, sudden stops, and cyclicality

    NARCIS (Netherlands)

    Li, Suxiao

    2017-01-01

    International fund flows are cross-border investments in domestic equity and bond markets by global investment funds. They have increased dramatically since the 1990s and played an increasingly important role in the transmission of shocks. In this thesis, we examine the drivers of large changes in f

  16. International fund flows: surges, sudden stops, and cyclicality

    NARCIS (Netherlands)

    Li, Suxiao

    2017-01-01

    International fund flows are cross-border investments in domestic equity and bond markets by global investment funds. They have increased dramatically since the 1990s and played an increasingly important role in the transmission of shocks. In this thesis, we examine the drivers of large changes in f

  17. Revealing glacier flow and surge dynamics from animated satellite image sequences: examples from the Karakoram

    Science.gov (United States)

    Paul, F.

    2015-11-01

    Although animated images are very popular on the internet, they have so far found only limited use for glaciological applications. With long time series of satellite images becoming increasingly available and glaciers being well recognized for their rapid changes and variable flow dynamics, animated sequences of multiple satellite images reveal glacier dynamics in a time-lapse mode, making the otherwise slow changes of glacier movement visible and understandable to the wider public. For this study, animated image sequences were created for four regions in the central Karakoram mountain range over a 25-year time period (1990-2015) from freely available image quick-looks of orthorectified Landsat scenes. The animations play automatically in a web browser and reveal highly complex patterns of glacier flow and surge dynamics that are difficult to obtain by other methods. In contrast to other regions, surging glaciers in the Karakoram are often small (10 km2 or less), steep, debris-free, and advance for several years to decades at relatively low annual rates (about 100 m a-1). These characteristics overlap with those of non-surge-type glaciers, making a clear identification difficult. However, as in other regions, the surging glaciers in the central Karakoram also show sudden increases of flow velocity and mass waves travelling down glacier. The surges of individual glaciers are generally out of phase, indicating a limited climatic control on their dynamics. On the other hand, nearly all other glaciers in the region are either stable or slightly advancing, indicating balanced or even positive mass budgets over the past few decades.

  18. Comprehensive Mapping of Ice Flow From Landsat 8: Two Years of Surging and Seasonal Change for Alaska's Glaciers, and Counting…

    Science.gov (United States)

    Fahnestock, M. A.; Larsen, C.; Truffer, M.; Scambos, T. A.; Gardner, A. S.

    2015-12-01

    While it has been known for years that rapid changes in ice flow occur on many Alaskan glaciers due to phenomena that span a gamut from tidewater glacier retreat to surging, it has not previously been possible to capture the spatial and temporal extent of this variability. We report on a comprehensive mapping effort, utilizing feature tracking in Landsat 8 imagery, that is producing a spatial and temporal picture of ice flow variations across southern and southeastern Alaska for glaciers half a kilometer in width and larger. We show that coverage and image characteristics for Landsat 8 enable sampling that is sufficient to track seasonal variations in flow speed for tidewater outlets; surge termination, initiation, and surge front propagation; and summer/winter flow variations for other land-terminating systems. Using the example of the 2014-15 surge of Walsh Glacier, seasonal changes on Columbia glacier, and comprehensive mosaics of ice flow across southern Alaska on a quarterly basis, we will demonstrate that we have entered an era when flow variations can be tracked in near real time, over large areas, with coverage suitable to follow evolving seasonal patterns even in frequently cloudy areas. As the Landsat 8 record continues to grow, it becomes possible to delimit surging and non-surging systems based on their flow speed history, rather than incomplete records of past flow and appearance.

  19. Environmental flow deficit at global scale - implication on irrigated agriculture

    Science.gov (United States)

    Pastor, Amandine; Ludwig, Fulco; Biemans, Hester; Kabat, Pavel

    2016-04-01

    Freshwater species belong to the most degraded ecosystem on earth. At the beginning of the 21st century, scientists have developed the concept of environmental flow requirements (Brisbane declaration 2003) with the aim of protecting freshwater species in the long term. However, the ecological state of rivers is different across the world depending on their fragmentation, on the presence of dams and reservoirs and on the degree of pollution. To implement new regulations on river flow, it is necessary to evaluate the degree of alteration of rivers which we called "environmental flow deficit". The European water framework directive is still working on evaluating the ecological states of river across Europe. In this study, we calculated monthly environmental flow deficit with the global vegetation dynamic and hydrological model LPJml. Environmental flow requirements were first calculated with the Variable Monthly Flow method (Pastor et al., 2014). Then, we checked in each river basin where and when the actual flow (flow minus abstraction for irrigation) does not satisfy environmental flow requirements. We finally show examples of different river basins such as the Nile and the Amazon to show how climate and irrigation can impact river flow and harm freshwater ecosystems.

  20. The future of irrigated agriculture under environmental flow requirements restrictions

    Science.gov (United States)

    Pastor, Amandine; Palazzo, Amanda; Havlik, Petr; Kabat, Pavel; Obersteiner, Michael; Ludwig, Fulco

    2016-04-01

    Water is not an infinite resource and demand from irrigation, household and industry is constantly increasing. This study focused on including global water availability including environmental flow requirements with water withdrawal from irrigation and other sectors at a monthly time-step in the GLOBIOM model. This model allows re-adjustment of land-use allocation, crop management, consumption and international trade. The GLOBIOM model induces an endogenous change in water price depending on water supply and demand. In this study, the focus was on how the inclusion of water resources affects land-use and, in particular, how global change will influence repartition of irrigated and rainfed lands at global scale. We used the climate change scenario including a radiative forcing of 8.5 W/m2 (RCP8.5), the socio-economic scenario (SSP2: middle-of-road), and the environmental flow method based on monthly flow allocation (the Variable Monthly Flow method) with high and low restrictions. Irrigation withdrawals were adjusted to a monthly time-step to account for biophysical water limitations at finer time resolution. Our results show that irrigated land might decrease up to 40% on average depending on the choice of EFR restrictions. Several areas were identified as future hot-spots of water stress such as the Mediterranean and Middle-East regions. Other countries were identified to be in safe position in terms of water stress such as North-European countries. Re-allocation of rainfed and irrigated land might be useful information for land-use planners and water managers at an international level to decide on appropriate legislations on climate change mitigation/adaptation when exposure and sensitivity to climate change is high and/or on adaptation measures to face increasing water demand. For example, some countries are likely to adopt measures to increase their water use efficiencies (irrigation system, soil and water conservation practices) to face water shortages, while

  1. Characterization of return flow pathways during flood irrigation

    Science.gov (United States)

    Claes, N.; Paige, G. B.; Parsekian, A.; Gordon, B. L.; Miller, S. N.

    2015-12-01

    With a decline in water resources available for private consumption and irrigation, the importance of sustainable water management practices is increasing. Local management decisions, based on models may affect the availability of water both locally and downstream, causing a ripple effect. It is therefore important that the models that these local management decisions are based on, accurately quantify local hydrological processes and the timescales at which they happen. We are focusing on return flow from flood irrigation, which can occur via different pathways back to the streams: overland flow, near-surface return flow and return flow via pathways below the vadose zone. The question addressed is how these different pathways each contribute to the total amount of return flow and the dynamics behind them. We used time-lapse ERT measurements in combination with an ensemble of ERT and seismic lines to answer this question via (1) capturing the process of gradual fragmentation of aqueous environments in the vadose zone during drying stages at field scale; (2) characterization of the formation of preferential flow paths from infiltrating wetting fronts during wetting cycles at field scale. The time-lapse ERT provides the possibility to capture the dynamic processes involved during the occurrence of finger flow or macro-pores when an intensive wetting period during flood irrigation occurs. It elucidates the dynamics of retention in the vadose zone during drying and wetting periods at field scale. This method provides thereby a link to upscale from laboratory experiments to field scale and watershed scale for finger flow and preferential flow paths and illustrates the hysteresis behavior at field scale.

  2. Active Flow Control in a Radial Vaned Diffuser for Surge Margin Improvement: A Multislot Suction Strategy

    Directory of Open Access Journals (Sweden)

    Aurélien Marsan

    2017-01-01

    Full Text Available This work is the final step of a research project that aims at evaluating the possibility of delaying the surge of a centrifugal compressor stage using a boundary-layer suction technique. It is based on Reynolds-Averaged Navier-Stokes numerical simulations. Boundary-layer suction is applied within the radial vaned diffuser. Previous work has shown the necessity to take into account the unsteady behavior of the flow when designing the active flow control technique. In this paper, a multislot strategy is designed according to the characteristics of the unsteady pressure field. Its implementation results in a significant increase of the stable operating range predicted by the unsteady RANS numerical model. A hub-corner separation still exists further downstream in the diffuser passage but does not compromise the stability of the compressor stage.

  3. Water temperature in irrigation return flow from the Upper Snake Rock watershed

    Science.gov (United States)

    Water returning to a river from an irrigated watershed could increase the water temperature in the river. The objective of this study was to compare the temperature of irrigation return flow water with the temperature of the diverted irrigation water. Water temperature was measured weekly in the mai...

  4. Effect of Coupling Wave and Flow Dynamics on Hurricane Surge and Inundation

    Science.gov (United States)

    2012-01-01

    impacted hurricanes - both by the wind fields as well as by the accompanying surge. Forecasting the extent of the inundation is critical for local...estimate local surge hazards; and in the other, ensemble model runs are used to determine surge values from a set of parameterized storms [Irish et...with the storm surge to create the storm tide. The extent of coastal inundation - flooding of inland surface that is not normally submerged, is

  5. Surge-damping vacuum valve

    Science.gov (United States)

    Bullock, Jack C.; Kelly, Benjamin E.

    1980-01-01

    A valve having a mechanism for damping out flow surges in a vacuum system which utilizes a slotted spring-loaded disk positioned adjacent the valve's vacuum port. Under flow surge conditions, the differential pressure forces the disk into sealing engagement with the vacuum port, thereby restricting the flow path to the slots in the disk damping out the flow surge.

  6. Objective rapid delineation of areas at risk from block-and-ash pyroclastic flows and surges

    Science.gov (United States)

    Widiwijayanti, C.; Voight, B.; Hidayat, D.; Schilling, S. P.

    2009-08-01

    Assessments of pyroclastic flow (PF) hazards are commonly based on mapping of PF and surge deposits and estimations of inundation limits, and/or computer models of varying degrees of sophistication. In volcanic crises a PF hazard map may be sorely needed, but limited time, exposures, or safety aspects may preclude fieldwork, and insufficient time or baseline data may be available for reliable dynamic simulations. We have developed a statistically constrained simulation model for block-and-ash type PFs to estimate potential areas of inundation by adapting methodology from Iverson et al. (Geol Soc America Bull 110:972-984, 1998) for lahars. The predictive equations for block-and-ash PFs are calibrated with data from several volcanoes and given by A = (0.05 to 0.1) V 2/3, B = (35 to 40) V 2/3, where A is cross-sectional area of inundation, B is planimetric area and V is deposit volume. The proportionality coefficients were obtained from regression analyses and comparison of simulations to mapped deposits. The method embeds the predictive equations in a GIS program coupled with DEM topography, using the LAHARZ program of Schilling (1998). Although the method is objective and reproducible, any PF hazard zone so computed should be considered as an approximate guide only, due to uncertainties on the coefficients applicable to individual PFs, the authenticity of DEM details, and the volume of future collapses. The statistical uncertainty of the predictive equations, which imply a factor of two or more in predicting A or B for a specified V, is superposed on the uncertainty of forecasting V for the next PF to descend a particular valley. Multiple inundation zones, produced by simulations using a selected range of volumes, partly accommodate these uncertainties. The resulting maps show graphically that PF inundation potentials are highest nearest volcano sources and along valley thalwegs, and diminish with distance from source and lateral distance from thalweg. The model

  7. Objective rapid delineation of areas at risk from block-and-ash pyroclastic flows and surges

    Science.gov (United States)

    Widiwijayanti, C.; Voight, B.; Hidayat, D.; Schilling, S.P.

    2009-01-01

    Assessments of pyroclastic flow (PF) hazards are commonly based on mapping of PF and surge deposits and estimations of inundation limits, and/or computer models of varying degrees of sophistication. In volcanic crises a PF hazard map may be sorely needed, but limited time, exposures, or safety aspects may preclude fieldwork, and insufficient time or baseline data may be available for reliable dynamic simulations. We have developed a statistically constrained simulation model for block-and-ash type PFs to estimate potential areas of inundation by adapting methodology from Iverson et al. (Geol Soc America Bull 110:972-984, (1998) for lahars. The predictive equations for block-and-ash PFs are calibrated with data from several volcanoes and given by A = (0.05 to 0.1) V2/3, B = (35 to 40) V2/3, where A is cross-sectional area of inundation, B is planimetric area and V is deposit volume. The proportionality coefficients were obtained from regression analyses and comparison of simulations to mapped deposits. The method embeds the predictive equations in a GIS program coupled with DEM topography, using the LAHARZ program of Schilling (1998). Although the method is objective and reproducible, any PF hazard zone so computed should be considered as an approximate guide only, due to uncertainties on the coefficients applicable to individual PFs, the authenticity of DEM details, and the volume of future collapses. The statistical uncertainty of the predictive equations, which imply a factor of two or more in predicting A or B for a specified V, is superposed on the uncertainty of forecasting V for the next PF to descend a particular valley. Multiple inundation zones, produced by simulations using a selected range of volumes, partly accommodate these uncertainties. The resulting maps show graphically that PF inundation potentials are highest nearest volcano sources and along valley thalwegs, and diminish with distance from source and lateral distance from thalweg. The model does

  8. GIS-based statistical mapping technique for block-and-ash pyroclastic flow and surge hazards

    Science.gov (United States)

    Widiwijayanti, C.; Voight, B.; Hidayat, D.; Schilling, S.

    2008-12-01

    Assessments of pyroclastic flow (PF) hazards are commonly based on mapping of PF and surge deposits and estimations of inundation limits, and/or computer models of varying degrees of sophistication. In volcanic crises a PF hazard map may be sorely needed, but limited time, exposures, or safety aspects may preclude fieldwork, and insufficient time or baseline data may be available for reliable dynamic simulations. We have developed a statistically constrained simulation model for block-and-ash PFs to estimate potential areas of inundation by adapting methodology from Iverson et al. (1998) for lahars. The predictive equations for block-and-ash PFs are calibrated with data from many volcanoes and given by A = (0.05-0.1)V2/3, B = (35-40)V2/3 , where A is cross-sectional area of inundation, B is planimetric area and V is deposit volume. The proportionality coefficients were obtained from regression analyses and comparison of simulations to mapped deposits. The method embeds the predictive equations in a GIS program coupled with DEM topography, using the LAHARZ program of Schilling (1998). Although the method is objective and reproducible, any PF hazard zone so computed should be considered as an approximate guide only, due to uncertainties on coefficients applicable to individual PFs, DEM details, and release volumes. Gradational nested hazard maps produced by these simulations reflect in a sense these uncertainties. The model does not explicitly consider dynamic behavior, which can be important. Surge impacts must be extended beyond PF hazard zones and we have explored several approaches to do this. The method has been used to supply PF hazard maps in two crises: Merapi 2006; and Montserrat 2006- 2007. We have also compared our hazard maps to actual recent PF deposits and to maps generated by several other model techniques.

  9. HYDRAULIC CHARACTERIZATIONS OF TORTUOUS FLOW IN PATH DRIP IRRIGATION EMITTER

    Institute of Scientific and Technical Information of China (English)

    LI Yun-kai; YANG Pei-ling; REN Shu-mei; XU Ting-wu

    2006-01-01

    At present, the tortuous emitter has the most advanced performances in drip irrigation. But the theories and methods for designing its flow path have been strictly confidential and the researches on the function of practical guidance have seldom been published. Seven types of most representative tortuous emitting-pipes currently used in agricultural irrigation regions of China were chosen for investigating the geometric parameters of the flow path by means of combining high-precision microscope and AutoCAD technology. By the measurement platform developed by the authors for hydraulic performances of emitters, the free discharge rates from the 7 types of emitters were measured at 9 pressure levels of 1.5 m, 3.0 m, 5.0 m, 7.0 m, 9.0 m, 10.0 m, 11.0 m, 13.0 m and 15.0 m. Then the discharge-pressure relationship, manufacturing variation coefficient, average velocity on the cross-section of flow path and the critical Reynolds number for the flow regime transformation within the paths were analyzed in detail. The results show that both pressure-ascending work pattern and pressure-descending work pattern have some impacts on the discharge rates of tortuous emitters, but the impact level is not significant. The target pressure could be approached by repetitive applications of the two work patterns during pressure regulation. The operation under low pressures has some impacts on the hydraulic performances of emitters, but the impact level is also not significant. The classical model of the discharge-pressure relationship is suitable for the pressure range of 1.5 m -15.0 m. The Reynolds number for fluids within the 7 types of tortuous emitters ranges from =105 to =930. The critical Reynolds number for the flow regime transformation is smaller than that for the routine dimension flow path. The variation coefficient of emitter discharge rates is slightly fluctuating around a certain value within the whole pressure range.

  10. Comparison of the flow characteristics of irrigants with standard and Max-i-Probe needles.

    Science.gov (United States)

    Devi, Arpana Arthi; Abbott, Paul V

    2012-08-01

    The objectives of this study were to determine the direction and pattern of flow of irrigating solutions inside simulated root canals with different irrigation needles; and to determine whether different needle designs increase the likelihood of irrigating solution passing through the apical foramen. Two types of needles were compared: a standard needle with a bevel and an open end, and a needle with a side opening and closed rounded tip. Observations of irrigant flow within the canals indicated that the side-venting needle can be dangerous if the needle gauge is small and it reaches the full length of the canal, since this allowed irrigants to flow into the periapical area. With the standard needle, the fluid did not go beyond the tip of the needle when minimal irrigating pressure was employed. As the size of canal increased, the fluid did not extrude beyond the tip of both needles. However, if the needles bound in the canals, then the fluid was forced away from the needle tip, and the pressure applied to the syringe was directly proportional to the distance the fluid flowed away from the needle tip. Both side-venting and standard needles can be used for irrigation safely and effectively if a dynamic irrigation technique (moving the needle up and down inside the canals while irrigating) is employed. © 2012 The Authors. Australian Endodontic Journal © 2012 Australian Society of Endodontology.

  11. Supplemental irrigation potential and impact on downstream flow of Karkheh River basin in Iran

    Science.gov (United States)

    Hessari, Behzad; Bruggeman, Adriana; Akhoond-Ali, Ali Mohammad; Oweis, Theib; Abbasi, Fariborz

    2016-05-01

    Supplemental irrigation of rainfed winter crops improves and stabilises crop yield and water productivity. Although yield increases by supplemental irrigation are well established at the field level, its potential extent and impact on water resources at the basin level are less researched. This work presents a Geographic Information Systems (GIS)-based methodology for identifying areas that are potentially suitable for supplemental irrigation and a computer routine for allocating streamflow for supplemental irrigation in different sub-basins. A case study is presented for the 42 908 km2 upper Karkheh River basin (KRB) in Iran, which has 15 840 km2 of rainfed crop areas. Rainfed crop areas within 1 km from the streams, with slope classes 0-5, 0-8, 0-12, and 0-20 %, were assumed to be suitable for supplemental irrigation. Four streamflow conditions (normal, normal with environmental flow requirements, drought and drought with environmental flow) were considered for the allocation of water resources. Thirty-seven percent (5801 km2) of the rainfed croplands had slopes less than 5 %; 61 % (3559 km2) of this land was suitable for supplemental irrigation, but only 22 % (1278 km2) could be served with irrigation in both autumn (75 mm) and spring (100 mm), under normal flow conditions. If irrigation would be allocated to all suitable land with slopes up to 20 %, 2057 km2 could be irrigated. This would reduce the average annual outflow of the upper KRB by 9 %. If environmental flow requirements are considered, a maximum (0-20 % slopes) of 1444 km2 could receive supplemental irrigation. Under drought conditions a maximum of 1013 km2 could be irrigated, while the outflow would again be reduced by 9 %. Thus, the withdrawal of streamflow for supplemental irrigation has relatively little effect on the outflow of the upper KRB. However, if the main policy goal would be to improve rainfed areas throughout the upper KRB, options for storing surface water need to be developed.

  12. Evaluation of Bubbler Irrigation System at Different Emission Flow Rates for Young Mango Orchard

    Directory of Open Access Journals (Sweden)

    Rajesh Kumar Soothar

    2016-08-01

    Full Text Available An experiment was conducted on evaluating performance of bubbler irrigation system under young mango plant rows at the Higher Education Commission, research station at Sindh Agriculture University, Tandojam. The experimental station possesses more than 70 mango plants, irrigated by micro and traditional irrigation methods fed by tubewell with average water static level of 9 ft below ground surface. Bubbler irrigation system was designed to irrigate 12 mango plants. The aim of study was to assess the performance of the bubbler irrigation system at different emission flow rates with an installed bubbler irrigation system to improve water distribution uniformity. The result of this study showed that the high pressure losses and the system operated on one gallon per minute flow rate of each bubbler, water distribution uniformity was low, with an average of 68 %. Other hand, comparison with emission (bubbler flow rate was adjusted at half gallon per minute has shown high water emission uniformity of system performed with an average of 92 % distribution uniformity. The reasons for the minimum distribution uniformity of bubblers were observed at one gallon per minute emission flow and this study recommended to improve the bubbler irrigation at dissimilar flow rates.

  13. A numerical analysis on generating process of intermittent debris flow surges

    Science.gov (United States)

    Arai, Muneyuki

    2016-04-01

    The generation of debris flow has some causes. This researche is on intermittent debris flow surges and due to mathematical approach of wave equation by numerical analysis. The following wave equation was obtained based on the momentum equation of shallow water. ∂η' '∂η' ∂2η' ∂3η' ∂τ' + a1η ∂ξ' - a2∂ξ'2 + a3∂ξ'3 = 0 (1) where, a1 = (3/2)c0'2, a2 = (1/2)( ) 1/c0'2 - 1/2tanθ (c0'/u0'), a3 = (1/2){ 4 2 } (2 + c0')/(2c0')- 3/2 , u0' = u0/c0, c0' = c0/vp0, c0 = √ ---- gh0cosθ, η' = η/h0, t' = tvp0/h0, ξ = ɛ1/2(x- vp0t), τ = ɛ3/2t, ξ' = ξ/h0 = ɛ1/2(x' - t'), τ' = ɛ3/2t', u0, h0 : velocity, depth of steady uniform flow, x : axis of flow direction, t : time, η : variance of flow surface from depth h0, θ : slope angle of the channel, g : acceleration due to gravity, ξ, τ : the Gardner-Morikawa transformation of x axis and time, ɛ : parameter of perturbative expansion, vp0 : phase velocity, c0 : long wave velocity, '(with prime) : non-dimensional variable. η' of equation (1) changes depending on the values of a1, a2, a3 on same section of ξ' and τ', and a1, a2 and a3 are function of c0'. c0' is ratio of long wave velocity and phase velocity, and c0' = 1 when phase velocity is equal to long wave velocity. For c0' = 1, then a3 = 0, the equation (1) becomes Burgers Equation, the waves deform to a wave of wave number one with increased phase velocity on progress at time. Therefor, the wave parts from Burgers equation and becomes the one that depend on equation (1) , KdV-Burgers equation. When the new phase velocity is grater than 1.04 times c0' (long wave velocity), waveform behaves as a solitary wave. This research shows these processes by some numerical solutions of equation (1).

  14. Cold basal conditions during surges control flow of fringing Arctic ice caps in Greenland

    Science.gov (United States)

    Cook, Samuel; Christoffersen, Poul; Todd, Joe; Palmer, Steven

    2017-04-01

    Fringing ice caps separated from larger ice sheets are rarely studied, yet they are an important part of earth's cryosphere, which has become the largest source of global sea-level rise. Understanding marginal ice caps is crucial for being able to predict sea-level change as they are responsible for up to 20% of Greenland's mass loss for 2003-2008. Studies of fringing ice caps can furthermore provide useful insights into processes operating on glaciers that surge. Surging has been the focus of much recent glaciological work, especially with reference to thermal evolution of polythermal glaciers in High Mountain Asia and the High Arctic. This has shown that the classic divide between hydrologically-controlled surges ('hard-bed') in Alaska and thermally-regulated ('soft-bed') surges elsewhere is less stark than previously assumed. Studying marginal ice caps can therefore be valuable in several ways. The largest fringing ice cap in Greenland is Flade Isblink. Previous work has established that this ice cap is showing a range of dynamic behaviour, including subglacial lake drainage and varied patterns of mass-balance change. In particular, a substantial surge, assumed to be caused by a version of the thermally-regulated mechanism, occurred between 1996 and 2000, making the ice cap a useful case study for investigating this process. Here we investigate the surge on Flade Isblink using the open-source, Full-Stokes model Elmer/Ice to invert for basal conditions and englacial temperatures using the adjoint method. We specifically study steady-state conditions representative of the active surge phase in 2000, and the subsequent quiescent phase, using patterns of surface velocity observed in 2000, 2005, 2008 and 2015. Under constant geometry, temperature and geothermal heat, it is shown that surging increases basal freezing rates by over 60% across an area that is twice as large as the area over which the bed freezes in the quiescent phase. The process responsible for this

  15. Investigating controls on debris-flow initiation and surge frequency at Chalk Cliffs, USA: initial results from monitoring and modeling

    Science.gov (United States)

    Kean, J. W.; McCoy, S. W.; Tucker, G. E.; Staley, D. M.; Coe, J. A.

    2012-04-01

    Recent monitoring of a small (0.3 km2) bedrock-dominated catchment in central Colorado, USA, has revealed distinct differences in debris-flow surge dynamics relative to rainfall intensity. Moderate bursts of rainfall (15-40 mm/hr) typically trigger a set of coarse-grained surges with depths that can exceed 1.0 m. High-intensity bursts of rainfall (40-150 mm/hr), in contrast, often generate only a single moderate-amplitude coarse-grained surge (> 0.5 m depth), followed by several minutes of water-rich flow having comparable or greater peak depth. In both cases, debris flows are observed within minutes of rain bursts due to the rapid concentration of runoff from bedrock cliffs to channels loaded with sediment from dry ravel and rockfall. Video observations have shown that the runoff can initiate debris flows both at a steep (~40 degree) bedrock-colluvium interface, and in a lower gradient (~15 degree) section of channel. This latter style of initiation, which has only been observed at moderate rainfall intensity, involves the formation and failure of a highly porous sediment dam created by bedload transport. We speculate that this process may be responsible for the creation of the consistent surge patterns we observe with moderate intensity rainfall, and may explain the relative lack of granular surges with high-intensity rainfall. To investigate this possibility, we have developed a simple one-dimensional morphodynamic model of the formation and failure of sediment dams in an undulating bedrock channel filled with loose bed sediment. The model consists of a coupled surface-subsurface water flow model, which is used to drive bed-sediment topographic adjustments based on the mathematical divergence of the sediment transport rate. Under certain topographic and water-flow conditions, the shear stress in a section of the channel can fall below the critical shear stress, resulting in local deposition of sediment. Consistent with field observations, the modeled deposit

  16. The effect of apical preparation size on irrigant flow in root canals evaluated using an unsteady Computational Fluid Dynamics model

    NARCIS (Netherlands)

    Boutsioukis, C.; Gogos, C.; Verhaagen, B.; Versluis, M.; Kastrinakis, E.; van der Sluis, L.W.M.

    2010-01-01

    Aim  To evaluate the effect of apical preparation size on irrigant flow inside a root canal during final irrigation with a syringe and two different needles types, using a Computational Fluid Dynamics (CFD) model. Methodology  A validated CFD model was used to simulate the irrigant flow from either

  17. Evaluation of irrigant flow in the root canal using different needle types by an unsteady computational fluid dynamics model

    NARCIS (Netherlands)

    Boutsioukis, C.; Verhaagen, B.; Versluis, M.; Kastrinakis, E.; Wesselink, P.R.; van der Sluis, L.W.M.

    2010-01-01

    Introduction The aim of this study was to evaluate the effect of needle tip design on the irrigant flow inside a prepared root canal during final irrigation with a syringe using a validated Computational Fluid Dynamics (CFD) model. Methods A CFD model was created to simulate the irrigant flow inside

  18. Evaluation of Irrigant Flow in the Root Canal Using Different Needle Types by an Unsteady Computational Fluid Dynamics Model

    NARCIS (Netherlands)

    Boutsioukis, Christos; Verhaagen, Bram; Versluis, Michel; Kastrinakis, Eleftherios; Wesselink, Paul R.; Sluis, van der Lucas W.M.

    2010-01-01

    Introduction: The aim of this study was to evaluate the effect of needle tip design on the irrigant flow inside a prepared root canal during final irrigation with a syringe using a validated Computational Fluid Dynamics (CFD) model. Methods: A CFD model was created to simulate the irrigant flow insi

  19. The effect of root canal taper on the irrigant flow: evaluation using an unsteady Computational Fluid Dynamics model

    NARCIS (Netherlands)

    Boutsioukis, C.; Gogos, C.; Verhaagen, B.; Versluis, M.; Kastrinakis, E.; van der Sluis, L.W.M.

    2010-01-01

    Aim  To evaluate the effect of root canal taper on irrigant flow inside a prepared root canal during final irrigation with a syringe and two types of needles, using a Computational Fluid Dynamics (CFD) model. Methodology  A validated CFD model was used to simulate irrigant flow from either a side-ve

  20. The effect of root canal taper on the irrigant flow: evaluation using an unsteady Computational Fluid Dynamics model

    NARCIS (Netherlands)

    Boutsioukis, C.; Gogos, C.; Verhaagen, B.; Versluis, M.; Kastrinakis, E.; Sluis, van der L.W.M.

    2010-01-01

    Aim  To evaluate the effect of root canal taper on irrigant flow inside a prepared root canal during final irrigation with a syringe and two types of needles, using a Computational Fluid Dynamics (CFD) model. Methodology  A validated CFD model was used to simulate irrigant flow from either a side-v

  1. Interrelations among pyroclastic surge, pyroclastic flow, and lahars in Smith Creek valley during first minutes of 18 May 1980 eruption of Mount St. Helens, USA

    Science.gov (United States)

    Brantley, S.R.; Waitt, R.B.

    1988-01-01

    A devastating pyroclastic surge and resultant lahars at Mount St. Helens on 18 May 1980 produced several catastrophic flowages into tributaries on the northeast volcano flank. The tributaries channeled the flows to Smith Creek valley, which lies within the area devastated by the surge but was unaffected by the great debris avalanche on the north flank. Stratigraphy shows that the pyroclastic surge preceded the lahars; there is no notable "wet" character to the surge deposits. Therefore the lahars must have originated as snowmelt, not as ejected water-saturated debris that segregated from the pyroclastic surge as has been inferred for other flanks of the volcano. In stratigraphic order the Smith Creek valley-floor materials comprise (1) a complex valley-bottom facies of the pyroclastic surge and a related pyroclastic flow, (2) an unusual hummocky diamict caused by complex mixing of lahars with the dry pyroclastic debris, and (3) deposits of secondary pyroclastic flows. These units are capped by silt containing accretionary lapilli, which began falling from a rapidly expanding mushroom-shaped cloud 20 minutes after the eruption's onset. The Smith Creek valley-bottom pyroclastic facies consists of (a) a weakly graded basal bed of fines-poor granular sand, the deposit of a low-concentration lithic pyroclastic surge, and (b) a bed of very poorly sorted pebble to cobble gravel inversely graded near its base, the deposit of a high-concentration lithic pyroclastic flow. The surge apparently segregated while crossing the steep headwater tributaries of Smith Creek; large fragments that settled from the turbulent surge formed a dense pyroclastic flow along the valley floor that lagged behind the front of the overland surge. The unusual hummocky diamict as thick as 15 m contains large lithic clasts supported by a tough, brown muddy sand matrix like that of lahar deposits upvalley. This unit contains irregular friable lenses and pods meters in diameter, blocks incorporated from

  2. Pyroclastic surges and flows from the 8-10 May 1997 explosive eruption of Bezymianny volcano, Kamchatka, Russia

    Science.gov (United States)

    Belousov, Alexander; Voight, Barry; Belousova, Marina; Petukhin, Anatoly

    2002-07-01

    The 8-10 May 1997 eruption of Bezymianny volcano began with extrusion of a crystallized plug from the vent in the upper part of the dome. Progressive gravitational collapses of the plug caused decompression of highly crystalline magma in the upper conduit, leading at 13:12 local time on 9 May to a powerful, vertical Vulcanian explosion. The dense pyroclastic mixture collapsed in boil-over style to generate a pyroclastic surge which was focused toward the southeast by the steep-walled, 1956 horseshoe-shaped crater. This surge, with a temperature 30 km2 with deposits as much as 30 cm thick and extending 7 km from the vent. The surge deposits comprised massive to vaguely laminated, gravelly sand (Md -1.2 to 3.7φ sorting 1.2 to 3φ) of poorly vesiculated andesite (mean density 1.82 g cm-3 vesicularity 30 vol% SiO2 content 58.0 wt%). The deposits, with a volume of 5-15×106 m3, became finer grained and better sorted with distance; the maximal diameter of juvenile clasts decreased from 46 to 4 cm. The transport and deposition of the surge over a snowy landscape generated extensive lahars which traveled >30 km. Immediately following the surge, semi-vesiculated block-and-ash flows were emplaced as far as 4.7 km from the vent. Over time the juvenile lava in clasts of these flows became progressively less crystallized, apparently more silicic (59.0 to 59.9 wt% SiO2) and more vesiculated (density 1.64 to 1.12 g cm-3 vesicularity 37 to 57 vol%). At this stage the eruption showed transitional behavior, with mass divided between collapsing fountain and buoyant column. The youngest pumice-and-ash flows were accompanied by a sustained sub-Plinian eruption column 14 km high, from which platy fallout clasts were deposited ( 59.7% SiO2; density 1.09 g cm-3 vesicularity 58 vol%). The explosive activity lasted about 37 min and produced a total of 0.026 km3 dense rock equivalent of magma, with an average discharge of 1.2×104 m3 s-1. A lava flow 200 m long terminated the eruption. The

  3. Winter speed-up of ice flow at quiescent surge-type glaciers in Yukon, Canada

    Science.gov (United States)

    Furuya, M.; Abe, T.

    2013-12-01

    Glacier surge exhibits order-of-magnitude faster velocity and km-scale terminus advance during its short active phase after a long quiescent period. The observations of glacier surge are still limited, and the mechanisms of glacier surge cycle remain elusive. Moreover, with the exception of several well-examined glaciers, the glacier dynamics during their quiescent periods remains even more uncertain due to the paucity of surface velocity measurement data. Here we examined spatial-temporal changes in the ice surface velocity of surge-type glaciers in the St. Elias Mountains near the border of Alaska and Yukon during the period from December 2006 to March 2011. We applied the offset-tracking (feature-tracking) technique to the L-band synthetic aperture radar (SAR) images derived from the Japanese Advanced Land Observation Satellite (ALOS). The Chitina, Anderson, Walsh, and Logan Glaciers, the major subpolar surge-type glaciers of the Chitina River valley system, could be examined with the highest temporal resolution because of the overlap of multiple satellite tracks. We have found significant upstream accelerations from fall to winter at a number of glaciers during their quiescence. Moreover, whereas the upstream propagating summer speed-up was observed, the winter speed-up propagated from upstream to downglacier. Although the winter speed-up seems to be at odds with the well-known summer speed-up, these observations are consistent with the fragmentary but well-known fact of glacier surge that often initiates in winter, suggesting that some of the mechanisms would be valid even during quiescent phases. Ice surface velocity at mountain glaciers and ice sheets typically exhibits the greatest acceleration from spring to early summer, followed by deceleration in mid-summer to fall, and is slowest in winter. These short-term velocity changes are attributed to subglacial slip associated with water pressure changes that occur because of the seasonal variability of

  4. Damage to structures by pyroclastic flows and surges, inferred from nuclear weapons effects

    Science.gov (United States)

    Valentine, Greg A.

    1998-12-01

    In order to define the risk from explosive eruptions, one must constrain both the probability of explosive events and the effects, or consequences, of those events. This paper focuses on the effects of pyroclastic flows and surges (here termed `pyroclastic density currents', or PDCs) on buildings, infrastructure elements, and to some extent on vehicles. PDCs impart a lateral force to such structures in the form of dynamic pressure, which depends on the bulk density of the PDC (which in turn depends mainly on particle concentration) and its velocity. For reasonable ranges of particle concentration (10 -3 to 0.5) and velocities (10 to 300 m/s), dynamic pressure on the upstream face of a structure ranges from ˜0.1 kPa to 10 4 kPa. Lateral loads ranging up to about 100 kPa were produced during nuclear weapons tests in the 1940s and 1950s that were designed to study the effects of such loading on a variety of structures for civil defense and emergency response purposes in the event of nuclear war. Although considerable simplifications are involved, the data from these weapon tests provide useful analog information for understanding the effects of PDCs. I reviewed data from the nuclear tests, describing the expected damage from different loadings. Tables are provided that define the response of different structural elements (e.g., windows, framing, walls) and whole structures to loading in probabilistic terms, which in principle account for variations in construction quality, orientation, and other factors. Finally, damage documented from historical eruptions at Mt. Lamington (1951), Herculaneum (AD 79 Vesuvius eruption), and St. Pierre (1902 Mt. Pelee eruption) is reviewed. Damage patterns, combined with estimates of velocity, provide an independent estimate of particle concentration in the PDCs. Details of structural damage should be recorded and mapped around future eruptions in order to help refine this aspect of consequence analysis. Another fruitful approach would

  5. Combined Wave and Surge Overtopping of Levees: Flow Hydrodynamics and Articulated Concrete Mat Stability

    Science.gov (United States)

    2008-08-01

    technical report describes small-scale physical model tests simulating combined wave and storm surge overtopping of a typical levee cross sec- tion of...journal article . The 2 percent run-up elevation should be estimated using the run-up formulas of de Waal and van der Meer (1992) or Hughes (2004). If van...to place the mats over some type of filter layer ( geotextile or stone filter) that prevents the levee or embankment soil from leeching out between

  6. 涌泉根灌多点源交汇入渗湿润体试验研究%Experimental Study on Soil Wetted Volume of Multiple Point Sources from Surge Root Irrigation Interference Infiltration

    Institute of Scientific and Technical Information of China (English)

    黎朋红; 汪有科; 马理辉; 赵颖娜; 黎朋军

    2011-01-01

    在米脂山地微灌枣树示范基地进行原状土涌泉根灌入渗试验,研究了多点源交汇入渗条件下涌泉根灌湿润体特征值的变化规律.结果表明,涌泉根灌多点源交汇入渗孔洞处和交汇面处的湿润锋运移距离与入渗时间均符合幂函数关系,交汇面处的湿润锋运移速度比孔洞处的快,最终交汇入渗湿润土体沿孔洞布置方向的剖面形状近似带状;在孔洞底部周围的中间区域土壤含水率等值线分布相对复杂,等值线的分布类似于地形图上的"鞍部";涌泉根灌双点源灌溉比单点源、四点源灌溉效果好.%Undisturbed soil surge root irrigation infiltration experiment was carried out at mountain microirrigation demonstration base for jujube at Mizhi, and the variation of eigenvalues of wetted soil is studied under the condition of multi-point source interference infiltration. Results show: the infiltration distance of soil wetted front were good power functional relation with infiltration time on the intersection surface side and the holes surface side under surge root irrigation, and the wetting front migration velocity at the intersection surface was faster than that at the hole, and that is, finally the profile shape of wetting soil under interference infiltration in the direction of hole arrangement would nearly become a ribbon. In the middle area around the hole bottom, the soil water content contour distribution was relatively complicated and the contour distribution was similar to the“saddle” on the topography. The double point sources irrigation got the best irrigation effect under surge root irrigation.

  7. Surge-type glaciers: controls, processes and distribution

    OpenAIRE

    Sevestre, Heïdi

    2015-01-01

    Glacier surging is an internally triggered instability. Surge-type glaciers periodically alternate between long periods of slow flow (the quiescent phase) and short periods of fast flow (the surge phase). Surging yields down-glacier transport of mass and often results in large and sudden glacier advances.The surging phenomenon has always challenged the notion of normality in glacier flow dynamics. The mechanisms of surging remain poorly understood. Observation of different surge behaviors acr...

  8. Evaluation of sap flow and trunk diameter sensors for irrigation scheduling in early maturing peach trees.

    Science.gov (United States)

    Conejero, W; Alarcón, J J; García-Orellana, Y; Nicolás, E; Torrecillas, A

    2007-12-01

    Five-year-old early maturing peach trees (Prunus persica (L.) Batsch cv. Flordastar grafted on GF-677 peach rootstock) were subjected to three irrigation treatments from March 18 to November 10, 2006. Control plants (T0 treatment) which received irrigation in excess of their crop water requirements (1089.7 mm) were compared with plants watered according to sap flow (SF; T1 treatment) or maximum daily trunk shrinkage (MDS; T2 treatment) measurements, so as to maintain SF and MDS signal intensities (control SF/SF in T1 and MDS in T2/control MDS, respectively) close to unity. When SF or MDS signal intensity on at least two of three consecutive days was at or below unity, irrigation was reduced by 10%. When the MDS signal intensity on at least two of three consecutive days exceeded unity, irrigation was increased by 10%. During the experiment, estimated crop evapotranspiration was 704.9 mm, and the cumulative amounts of applied water in the T1 and T2 treatments were 463.2 and 654.5 mm, respectively. The MDS-signal-intensity-driven irrigation schedule was more suitable than the SF-signal-intensity-driven irrigation schedule because it was more sensitive and reliable in detecting changes in plant water status, preventing the development of detectable plant water stress. Moreover, it had no effect on fruit size. We conclude that peach tree irrigation scheduling can be based on MDS measurements alone. Changes in the irrigation protocol assayed were proposed to reduce MDS signal intensity deviations above unity, for example, by increasing the irrigation scheduling frequency or the amount of water applied, or both. Irrigation schedules based on maintaining MDS signal intensities close to unity could be applied when local crop factor values are unavailable.

  9. Effect of irrigation return flow on groundwater recharge in an overexploited aquifer in Bangladesh

    Science.gov (United States)

    Touhidul Mustafa, Syed Md.; Shamsudduha, Mohammad; Huysmans, Marijke

    2016-04-01

    Irrigated agriculture has an important role in the food production to ensure food security of Bangladesh that is home to over 150 million people. However, overexploitation of groundwater for irrigation, particularly during the dry season, causes groundwater-level decline in areas where abstraction is high and surface geology inhibits direct recharge to underlying shallow aquifer. This is causing a number of potential adverse socio-economic, hydrogeological, and environmental problems in Bangladesh. Alluvial aquifers are primarily recharged during monsoon season from rainfall and surface sources. However, return flow from groundwater-fed irrigation can recharge during the dry months. Quantification of the effect of return flow from irrigation in the groundwater system is currently unclear but thought to be important to ensure sustainable management of the overexploited aquifer. The objective of the study is to investigate the effect of irrigation return flow on groundwater recharge in the north-western part of Bangladesh, also known as Barind Tract. A semi-physically based distributed water balance model (WetSpass-M) is used to simulate spatially distributed monthly groundwater recharge. Results show that, groundwater abstraction for irrigation in the study area has increased steadily over the last 29 years. During the monsoon season, local precipitation is the controlling factor of groundwater recharge; however, there is no trend in groundwater recharge during that period. During the dry season, however, irrigation return-flow plays a major role in recharging the aquifer in the irrigated area compared to local precipitation. Therefore, during the dry season, mean seasonal groundwater recharge has increased and almost doubled over the last 29 years as a result of increased abstraction for irrigation. The increase in groundwater recharge during dry season has however no significant effect in the improvement of groundwater levels. The relation between groundwater

  10. Coexisting state of surge and rotating stall in a two-stage axial flow compressor using a double-phase-locked averaging technique

    Science.gov (United States)

    Sakata, Yuu; Ohta, Yutaka

    2017-02-01

    The interaction between surge and rotating stall in an axial flow compressor was investigated from the viewpoint of an unsteady inner flow structure. The aim of this study was to identify the key factor that determines the switching phenomenon of a surge cycle. The main feature of the tested compressor is a shock tube connected in series to the compressor outlet through a diaphragm, slits, and a concentric duplex pipe: this system allows surge and rotating stall to be generated by connecting the shock tube with the compressor, or enables the compression plane wave injection. The unsteady characteristics and the internal flow velocity fluctuations were measured in detail, and the stall cell structure was averaged and visualized along the movement of the operation point under a coexisting state of surge. A coefficient of the cell scale fluctuation was calculated using the result of the averaging, and it confirmed that the processes of inner flow structure change differed from each other according to the next cycle of the surge. The result suggests that the key factor that determines the next cycle is the transformation of the internal flow structure, particularly between the stall cell and the entire circumferential stall, in both the recovering and stalling processes.

  11. Groundwater Abstraction for Irrigation and Its Impacts on Low Flows in a Watershed in Northwest Germany

    Directory of Open Access Journals (Sweden)

    Hartmut Wittenberg

    2015-07-01

    Full Text Available Low flows of the Ilmenau River (1434 km2 in northwest Germany have decreased by about 25% over the last 50 years. In the same period, moderate climate changes have taken place and annual groundwater abstractions for sprinkler irrigation have increased by up to 50 hm3 (million m3, with a strong variation due to the respective prevailing weather conditions. Time-series analyses with multiple regression analysis allow detecting and quantifying different influences on low flows. It is also shown that farmers allocate irrigation water volumes carefully according to seasonal precipitation and temperatures. Decline of groundwater levels in summer and the low flow situation are aggravated by the cumulative effect of higher irrigation in drier years. Groundwater recharge and recovery of the water table have been observed subsequently during the winter season.

  12. Nitrogen and salt loads in the irrigation return flows of the Ebro River Basin (Spain)

    Science.gov (United States)

    Isidoro, Daniel; Balcells, Maria; Clavería, Ignacio; Dechmi, Farida; Quílez, Dolores; Aragüés, Ramón

    2013-04-01

    The conservation of the quality of surface waters demanded by the European Water Framework Directive requires, among others, an assessment of the irrigation-induced pollution. The contribution of the irrigation return flows (IRF) to the pollution of the receiving water bodies is given by its pollutant load, since this load determines the quality status or pollutant concentration in these water bodies. The aim of this work was to quantify the annual nitrogen and salt loads in the IRF of four irrigated catchments within the Ebro River Basin: Violada (2006-10), Alcanadre (2008-10), Valcuerna (2010), and Clamor Amarga (2010). The daily flow (Q), salt (EC) and nitrate concentration (NO3) were measured in the drainage outlets of each basin. The net irrigation-induced salt and nitrogen loads were obtained from these measurements after discounting the salt and nitrogen inputs from outside the catchments and the non-irrigated areas. The N-fertilizer applications were obtained from farmer surveys and animal farming statistical sources. Irrigation water salinity was very low in all catchments (EC corn-dominated Valcuerna in 2010 to 63 kg/ha in 2008 in Violada, when farmers barely applied fertilizers due to the irrigation modernization works in progress that year. The highest N applications derived from pig slurry applications by farmers that used their lands as disposal sites for their farm residues. The highest NO3 concentrations (mean of 113 mg/L) and annual N loads (mean of 38 kg/ha) were found in Valcuerna, the most intense corn sprinkler-irrigated catchment. The lowest NO3 concentrations (21 mg/L; 5 times lower than Valcuerna) were measured in the Alcanadre flood-irrigated catchment. In contrast, Alcanadre N loads (21 kg/ha) were only about two times lower than in Valcuerna, due to the higher IRF volumes in Alcanadre (353 mm versus 132 mm in Valcuerna). Irrigation modernization in Violada decreased N loads from 20 to 5 kg N/ha (four times lower) due to the sharp

  13. Closing the irrigation deficit in Cambodia: Implications for transboundary impacts on groundwater and Mekong River flow

    Science.gov (United States)

    Erban, Laura E.; Gorelick, Steven M.

    2016-04-01

    Rice production in Cambodia, essential to food security and exports, is largely limited to the wet season. The vast majority (96%) of land planted with rice during the wet season remains fallow during the dry season. This is in large part due to lack of irrigation capacity, increases in which would entail significant consequences for Cambodia and Vietnam, located downstream on the Mekong River. Here we quantify the extent of the dry season "deficit" area in the Cambodian Mekong River catchment, using a recent agricultural survey and our analysis of MODIS satellite data. Irrigation of this land for rice production would require a volume of water up to 31% of dry season Mekong River flow to Vietnam. However, the two countries share an aquifer system in the Mekong Delta, where irrigation demand is increasingly met by groundwater. We estimate expansion rates of groundwater-irrigated land to be >10% per year in the Cambodian Delta using LANDSAT satellite data and simulate the effects of future expansion on groundwater levels over a 25-year period. If groundwater irrigation continues to expand at current rates, the water table will drop below the lift limit of suction pump wells, used for domestic supply by >1.5 million people, throughout much of the area within 15 years. Extensive groundwater irrigation jeopardizes access for shallow domestic water supply wells, raises the costs of pumping for all groundwater users, and may exacerbate arsenic contamination and land subsidence that are already widespread hazards in the region.

  14. 3-D simulation of transient flow patterns in a corridor-shaped air-cushion surge chamber based on computational fluid dynamics

    Institute of Scientific and Technical Information of China (English)

    XIA Lin-sheng; CHENG Yong-guang; ZHOU Da-qing

    2013-01-01

    The 3-D characteristics of the water-air flow patterns in a corridor-shaped air-cushion surge chamber during hydraulic transients need to be considered in the shape optimization.To verify the reliability of the water-air two-phase model,namely,the volume of fluid model,the process of charging water into a closed air chamber is successfully simulated.Using the model,the 3-D flow characteristics under the load rejection and acceptance conditions within the air-cushion surge chamber of a specific hydropower station are studied.The flee surface waves,the flow patterns,and the pressure changes during the surge wave process are analyzed in detail.The longitudinal flow of water in the long corridor-shaped surge chamber is similar to the open channel flow with respect to the wave propagation,reflection and superposition characteristics.The lumped parameters of the 3-D numerical simulation agree with the results of a 1-D calculation of hydraulic transients in the whole water conveying system,which validates the 3-D method.The 3-D flow structures obtained can be applied to the shape optimization of the chamber.

  15. An in vivo assessment of the influence of needle gauges on endodontic irrigation flow rate

    Directory of Open Access Journals (Sweden)

    Velayutham Gopikrishna

    2016-01-01

    Statistical Analysis Used: The following tests were used for the statistical analysis: Independent sample "T" test, one-way ANOVA test, and post hoc multiple comparison was carried out using Tukey′s honest significant difference (HSD test using Statistical Package for the Social Sciences (SPSS version 16 for Windows. Results: The average flow rate of 26 gauge was 0.27 mLs−1 , of 27 gauge was 0.19 mLs−1 , and of 30 gauge was 0.09 mls−1 . There was statistical significance among the gauges (P < 0.001. 26 gauge had highest flow rate when compared with other groups followed by 27 gauge and 30 gauge respectively. The operator variability for flow rate of three endodontic irrigation needle gauges (26 gauge, 27 gauge, and 30 gauge was found to be not significant. Conclusions: Needle gauge has significant influence on endodontic irrigation flow rate.

  16. A global, spatially-explicit assessment of irrigated croplands influenced by urban wastewater flows

    Science.gov (United States)

    Thebo, A. L.; Drechsel, P.; Lambin, E. F.; Nelson, K. L.

    2017-07-01

    When urban areas expand without concomitant increases in wastewater treatment capacity, vast quantities of wastewater are released to surface waters with little or no treatment. Downstream of many urban areas are large areas of irrigated croplands reliant on these same surface water sources. Case studies document the widespread use of untreated wastewater in irrigated agriculture, but due to the practical and political challenges of conducting a true census of this practice, its global extent is not well known except where reuse has been planned. This study used GIS-based modeling methods to develop the first spatially-explicit estimate of the global extent of irrigated croplands influenced by urban wastewater flows, including indirect wastewater use. These croplands were further classified by their likelihood of using poor quality water based on the spatial proximity of croplands to urban areas, urban wastewater return flow ratios, and proportion of wastewater treated. This study found that 65% (35.9 Mha) of downstream irrigated croplands were located in catchments with high levels of dependence on urban wastewater flows. These same catchments were home to 1.37 billion urban residents. Of these croplands, 29.3 Mha were located in countries with low levels of wastewater treatment and home to 885 million urban residents. These figures provide insight into the key role that water reuse plays in meeting the water and food needs of people around the world, and the need to invest in wastewater treatment to protect public health.

  17. Generation of pyroclastic flows and surges by hot-rock avalanches from the dome of Mount St. Helens volcano, USA

    Science.gov (United States)

    Mellors, R.A.; Waitt, R.B.; Swanson, D.A.

    1988-01-01

    Several hot-rock avalanches have occurred during the growth of the composite dome of Mount St. Helens, Washington between 1980 and 1987. One of these occurred on 9 May 1986 and produced a fan-shaped avalanche deposit of juvenile dacite debris together with a more extensive pyroclastic-flow deposit. Laterally thinning deposits and abrasion and baking of wooden and plastic objects show that a hot ash-cloud surge swept beyond the limits of the pyroclastic flow. Plumes that rose 2-3 km above the dome and vitric ash that fell downwind of the volcano were also effects of this event, but no explosion occurred. All the facies observed originated from a single avalanche. Erosion and melting of craterfloor snow by the hot debris caused debris flows in the crater, and a small flood that carried juvenile and other clasts north of the crater. A second, broadly similar event occured in October 1986. Larger events of this nature could present a significant volcanic hazard. ?? 1988 Springer-Verlag.

  18. Evaluation of diffuse and preferential flow pathways of infiltratedprecipitation and irrigation using oxygen and hydrogen isotopes

    Science.gov (United States)

    Ma, Bin; Liang, Xing; Liu, Shaohua; Jin, Menggui; Nimmo, John R.; Li, Jingxin

    2017-01-01

    Subsurface-water flow pathways in three different land-use areas (non-irrigated grassland, poplar forest, and irrigated arable land) in the central North China Plain were investigated using oxygen (18O) and hydrogen (2H) isotopes in samples of precipitation, soils, and groundwater. Soil water in the top 10 cm was significantly affected by both evaporation and infiltration. Water at 10–40 cm depth in the grassland and arable land, and 10–60 cm in poplar forest, showed a relatively short residence time, as a substantial proportion of antecedent soil water was mixed with a 92-mm storm infiltration event, whereas below those depths (down to 150 cm), depleted δ18O spikes suggested that some storm water bypassed the shallow soil layers. Significant differences, in soil-water content and δ18O values, within a small area, suggested that the proportion of immobile soil water and water flowing in subsurface pathways varies depending on local vegetation cover, soil characteristics and irrigation applications. Soil-water δ18O values revealed that preferential flow and diffuse flow coexist. Preferential flow was active within the root zone, independent of antecedent soil-water content, in both poplar forest and arable land, whereas diffuse flow was observed in grassland. The depleted δ18O spikes at 20–50 cm depth in the arable land suggested the infiltration of irrigation water during the dry season. Temporal isotopic variations in precipitation were subdued in the shallow groundwater, suggesting more complete mixing of different input waters in the unsaturated zone before reaching the shallow groundwater.

  19. Partitioning groundwater recharge between rainfall infiltration and irrigation return flows using stable isotopes: the Crau aquifer.

    Science.gov (United States)

    Seraphin, Pierre; Vallet-Coulomb, Christine; Gonçalvès, Julio

    2016-04-01

    Traditional flood irrigation is used since the 16th century in the Crau plain (Southern France) for hay production. To supply this high consuming irrigation practice, water is diverted from the Durance River, originating from the Alps, and the large amount of irrigation return flows constitutes the main recharge of the Crau aquifer, which is in turn largely exploited for domestic, industrial and agricultural water use. A possible reduction of irrigation fluxes due to a need of water saving or to a future land-use change could endanger the groundwater resource. A robust quantification of the groundwater mass balance is thus required to assess a sustainable water management in the region. The high isotopic contrast between these exogenous irrigation waters and local precipitations allows the use of stable isotopes of water as conservative tracers to deduce their contributions to the surface recharge. An extensive groundwater sampling was performed to obtain δ18O and δ2H over the whole aquifer. Based on a new piezometric contour map, combined with a reestimate of the aquifer geometry, the isotopic data are implemented in a geostatistical approach to produce a conceptual equivalent-homogeneous reservoir, in order to apply a simple water and isotope mass balance mixing model. The isotopic composition of the two end-members is assessed, and the quantification of groundwater flows is then used to calculate the two recharge fluxes. Near to steady-state condition, the set of isotopic data treated by geostatistics leads to a recharge by irrigation of 5.20 ± 0.93 m3 s-1 i.e. 1173 ± 210 mm yr-1, and a natural recharge of 2.26 ± 0.91 m3 s-1 i.e. 132 ± 53 mm yr-1. Thus, 70 ± 9% of the effective surface recharge comes from the irrigation return flow, consistent with the literature (between 67% and 78%). This study constitutes a straightforward and independent approach to assess groundwater surface recharges with uncertainties and will help to constrain a future transient

  20. Irrigant flow in the root canal: experimental validation of an unsteady Computational Fluid Dynamics model using high-speed imaging

    NARCIS (Netherlands)

    Boutsioukis, C.; Verhaagen, B.; Versluis, M.; Kastrinakis, E.; Sluis, van der L.W.M.

    2010-01-01

    Aim  To compare the results of a Computational Fluid Dynamics (CFD) simulation of the irrigant flow within a prepared root canal, during final irrigation with a syringe and a needle, with experimental high-speed visualizations and theoretical calculations of an identical geometry and to evaluate the

  1. Irrigant flow in the root canal: experimental validation of an unsteady computational fluid dynamics model using high-speed imaging

    NARCIS (Netherlands)

    C. Boutsioukis; B. Verhaagen; M. Versluis; E. Kastrinakis; L.W.M. van der Sluis

    2010-01-01

    Aim  To compare the results of a Computational Fluid Dynamics (CFD) simulation of the irrigant flow within a prepared root canal, during final irrigation with a syringe and a needle, with experimental high-speed visualizations and theoretical calculations of an identical geometry and to evaluate the

  2. Countercurrent Flow Limitation at the Junction between the Surge Line and the Pressurizer of a PWR

    Directory of Open Access Journals (Sweden)

    Taiga Doi

    2012-01-01

    Full Text Available An experimental study on countercurrent flow limitation (CCFL in vertical pipes is carried out. Effects of upper tank geometry and water levels in the upper and lower tanks on CCFL characteristics are investigated for air-water two-phase flows at room temperature and atmospheric pressure. The following conclusions are obtained: (1 CCFL characteristics for different pipe diameters are well correlated using the Kutateladze number if the tank geometry and the water levels are the same; (2 CCFL occurs at the junction between the pipe and the upper tank both for the rectangular and cylindrical tanks, and CCFL with the cylindrical tank occurs not only at the junction but also inside the pipe at high gas flow rates and small pipe diameters; (3 the flow rate of water entering into the vertical pipe at the junction to the rectangular upper tank is lower than that to the cylindrical tank because of the presence of low frequency first-mode sloshing in the rectangular tank; (4 increases in the water level in the upper tank and in the air volume in the lower tank increase water penetration into the pipe, and therefore, they mitigate the flow limitation.

  3. Combined effects of projected sea level rise, storm surge, and peak river flows on water levels in the Skagit Floodplain

    Science.gov (United States)

    Hamman, Josheph J; Hamlet, Alan F.; Fuller, Roger; Grossman, Eric

    2016-01-01

    Current understanding of the combined effects of sea level rise (SLR), storm surge, and changes in river flooding on near-coastal environments is very limited. This project uses a suite of numerical models to examine the combined effects of projected future climate change on flooding in the Skagit floodplain and estuary. Statistically and dynamically downscaled global climate model scenarios from the ECHAM-5 GCM were used as the climate forcings. Unregulated daily river flows were simulated using the VIC hydrology model, and regulated river flows were simulated using the SkagitSim reservoir operations model. Daily tidal anomalies (TA) were calculated using a regression approach based on ENSO and atmospheric pressure forcing simulated by the WRF regional climate model. A 2-D hydrodynamic model was used to estimate water surface elevations in the Skagit floodplain using resampled hourly hydrographs keyed to regulated daily flood flows produced by the reservoir simulation model, and tide predictions adjusted for SLR and TA. Combining peak annual TA with projected sea level rise, the historical (1970–1999) 100-yr peak high water level is exceeded essentially every year by the 2050s. The combination of projected sea level rise and larger floods by the 2080s yields both increased flood inundation area (+ 74%), and increased average water depth (+ 25 cm) in the Skagit floodplain during a 100-year flood. Adding sea level rise to the historical FEMA 100-year flood resulted in a 35% increase in inundation area by the 2040's, compared to a 57% increase when both SLR and projected changes in river flow were combined.

  4. A New Model for Predicting Dynamic Surge Pressure in Gas and Drilling Mud Two-Phase Flow during Tripping Operations

    Directory of Open Access Journals (Sweden)

    Xiangwei Kong

    2014-01-01

    Full Text Available Investigation of surge pressure is of great significance to the circulation loss problem caused by unsteady operations in management pressure drilling (MPD operations. With full consideration of the important factors such as wave velocity, gas influx rate, pressure, temperature, and well depth, a new surge pressure model has been proposed based on the mass conservation equations and the momentum conservation equations during MPD operations. The finite-difference method, the Newton-Raphson iterative method, and the fourth-order explicit Runge-Kutta method (R-K4 are adopted to solve the model. Calculation results indicate that the surge pressure has different values with respect to different drill pipe tripping speeds and well parameters. In general, the surge pressure tends to increase with the increases of drill pipe operating speed and with the decrease of gas influx rate and wellbore diameter. When the gas influx occurs, the surge pressure is weakened obviously. The surge pressure can cause a significant lag time if the gas influx occurs at bottomhole, and it is mainly affected by pressure wave velocity. The maximum surge pressure may occur before drill pipe reaches bottomhole, and the surge pressure is mainly affected by drill pipe operating speed and gas influx rate.

  5. Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates

    NARCIS (Netherlands)

    Percin, M.; Van Oudheusden, B.W.

    2015-01-01

    Tomographic particle image velocimetry was used to explore the evolution of three-dimensional flow structures of revolving low-aspect-ratio flat plates in combination with force measurements at a Reynolds number of 10,000. Two motion kinematics are compared that result in the same terminal condition

  6. Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates

    NARCIS (Netherlands)

    Percin, M.; Van Oudheusden, B.W.

    2015-01-01

    Tomographic particle image velocimetry was used to explore the evolution of three-dimensional flow structures of revolving low-aspect-ratio flat plates in combination with force measurements at a Reynolds number of 10,000. Two motion kinematics are compared that result in the same terminal condition

  7. Partitioning groundwater recharge between rainfall infiltration and irrigation return flow using stable isotopes: The Crau aquifer

    Science.gov (United States)

    Séraphin, Pierre; Vallet-Coulomb, Christine; Gonçalvès, Julio

    2016-11-01

    This study reports an assessment of the water budget of the Crau aquifer (Southern France), which is poorly referenced in the literature. Anthropogenically controlled by a traditional irrigation practice, this alluvial type aquifer requires a robust quantification of the groundwater mass balance in order to establish sustainable water management in the region. In view of the high isotopic contrast between exogenous irrigation waters and local precipitations, stable isotopes of water can be used as conservative tracers to deduce their contributions to the surface recharge. Extensive groundwater sampling was performed to obtain δ18O and δ2H over the whole aquifer. Based on a new piezometric contour map, combined with an updated aquifer geometry, the isotopic data were implemented in a geostatistical approach to produce a conceptual equivalent homogeneous reservoir. This makes it possible to implement a parsimonious water and isotope mass-balance mixing model. The isotopic compositions of the two end-members were assessed, and the quantification of groundwater flows was then used to calculate the two recharge fluxes (natural and irrigation). Nearly at steady-state, the set of isotopic data treated by geostatistics gave a recharge by irrigation of 4.92 ± 0.89 m3 s-1, i.e. 1109 ± 202 mm yr-1, and a natural recharge of 2.19 ± 0.85 m3 s-1, i.e. 128 ± 50 mm yr-1. Thus, 69 ± 9% of the surface recharge is caused by irrigation return flow. This study constitutes a straightforward and independent approach to assess groundwater surface recharges including uncertainties and will help to constrain future transient groundwater models of the Crau aquifer.

  8. Heterogeneity in Karakoram glacier surges

    Science.gov (United States)

    Quincey, Duncan J.; Glasser, Neil F.; Cook, Simon J.; Luckman, Adrian

    2015-07-01

    Many Karakoram glaciers periodically undergo surges during which large volumes of ice and debris are rapidly transported downglacier, usually at a rate of 1-2 orders of magnitude greater than during quiescence. Here we identify eight recent surges in the region and map their surface velocities using cross-correlation feature tracking on optical satellite imagery. In total, we present 44 surface velocity data sets, which show that Karakoram surges are generally short-lived, lasting between 3 and 5 years in most cases, and have rapid buildup and relaxation phases, often lasting less than a year. Peak velocities of up to 2 km a-1 are reached during summer months, and the surges tend to diminish during winter months. Otherwise, they do not follow a clearly identifiable pattern. In two of the surges, the peak velocity travels down-ice through time as a wave, which we interpret as a surge front. Three other surges are characterized by high velocities that occur simultaneously across the entire glacier surface, and acceleration and deceleration are close to monotonic. There is also no consistent seasonal control on surge initiation or termination. We suggest that the differing styles of surge can be partly accounted for by individual glacier configurations and that while some characteristics of Karakoram surges are akin to thermally controlled surges elsewhere (e.g., Svalbard), the dominant surge mechanism remains unclear. We thus propose that these surges represent a spectrum of flow instabilities and the processes controlling their evolution may vary on a glacier by glacier basis.

  9. Revealing glacier flow and surge dynamics from animated satellite image sequences: examples from the Karakoram

    OpenAIRE

    Paul, F

    2015-01-01

    Although animated images are very popular on the internet, they have so far found only limited use for glaciological applications. With long time series of satellite images becoming increasingly available and glaciers being well recognized for their rapid changes and variable flow dynamics, animated sequences of multiple satellite images reveal glacier dynamics in a time-lapse mode, making the otherwise slow changes of glacier movement visible and understandable to the wider...

  10. Analytical Calculation of Stall-inception and Surge Points for an Axial-flow Compresor Rotor

    OpenAIRE

    Moreno Benavides, Efren; López Juste, Gregorio

    2012-01-01

    Recently, a theoretical criterion to calculate the stability of an axial-flow compressor rotor has been presented in the scientific literature. This theoretical criterion was used for determining the locus of the stability line over the rotor map and for predicting the post-stall evolution of the constant-speed line of a rotor. The main objective of this paper is to improve the predictions of such a model. To do that, the paper proposes a different characterization of the characteristic az...

  11. Inland-directed base surge generated by the explosive interaction of pyroclastic flows and seawater at Soufrière Hills volcano, Montserrat

    Science.gov (United States)

    Edmonds, Marie; Herd, Richard A.

    2005-01-01

    The largest and most intense lava-dome collapse during the eruption of Soufrière Hills volcano, Montserrat, 1995–2004, occurred 12–13 July 2003. The dome collapse involved around 200 × 106 m3 of material and was associated with a phenomenon previously unknown at this volcano. Large pyroclastic flows at the peak of the dome collapse interacted explosively with seawater at the mouth of the Tar River Valley and generated a hot, dry base surge that flowed 4 km inland and 300 m uphill. The surge was destructive to at least 25 m above the ground and it carbonized vegetation. The resulting two-layer deposits were as much as 0.9 m thick. Although the entire collapse lasted 18 h, the base surge greatly increased the land area affected by the dome collapse in a few minutes at the peak of the event, illustrating the complex nature of the interaction between pyroclastic flows and seawater.

  12. Preferential flow, nitrogen transformations and 15N balance under urine-affected areas of irrigated and non-irrigated clover-based pastures

    Science.gov (United States)

    Pakro, Naser; Dillon, Peter

    1995-12-01

    Urine-affected areas can lead to considerable losses of N by leaching, ammonia volatilisation and denitrification from dairy pastures in the southeast of South Australia. Potable groundwater supplies are considered to have become contaminated by nitrate as a result of leaching from these leguminous pastures. Dairy cow urine, labelled with 15N urea, was applied to micro-plots and mini-lysimeters installed in two adjacent irrigated (white clover-rye grass) and non-irrigated (subterranean clover-annual grasses) paddocks of a dairy farm on four occasions representing different seasonal conditions. These experiments allowed measurement of nitrogen transformations, recovery of 15N in the pasture and soil, and leaching below various depths. Gaseous losses were calculated from the nitrogen balance. The results of the four experiments showed that within a day of urine application up to 40% of the applied urinary-N was leached below a depth of 150 mm as a result of macropore flow in the irrigated paddock, and up to 24% in the non-irrigated one. After application to the irrigated paddock 17% of the urinary-N moved immediately below 300 mm but only 2% below the 450-mm depth. The urinary-N remaining in the soil was converted from urea to ammonium within a day regardless of season. Within the first 7 days of application six times more nitrate was produced in summer than in winter. This has obvious implications for leaching potential. Leaching of 15N from the top 150 mm of soil, following urine applications in all seasons, was between 41% and 62% of the applied 15N in the irrigated paddock and 25-51% in the non-irrigated paddock. However, leaching losses measured at depths of 300 or 450 mm were smaller by a factor of 2-4. The leaching loss of 15N applied in spring in both paddocks was 41% below 150 mm and 12% below 450 mm. Recovery of 15N from the soil-plant system in the 450-nm deep lysimeters was ˜60% of that applied. Estimated ammonia was ˜9% of applied 15N with no paddock

  13. Reconciling irrigated food production with environmental flows for Sustainable Development Goals implementation

    Science.gov (United States)

    Jägermeyr, Jonas; Pastor, Amandine; Biemans, Hester; Gerten, Dieter

    2017-07-01

    Safeguarding river ecosystems is a precondition for attaining the UN Sustainable Development Goals (SDGs) related to water and the environment, while rigid implementation of such policies may hamper achievement of food security. River ecosystems provide life-supporting functions that depend on maintaining environmental flow requirements (EFRs). Here we establish gridded process-based estimates of EFRs and their violation through human water withdrawals. Results indicate that 41% of current global irrigation water use (997 km3 per year) occurs at the expense of EFRs. If these volumes were to be reallocated to the ecosystems, half of globally irrigated cropland would face production losses of >=10%, with losses of ~20-30% of total country production especially in Central and South Asia. However, we explicitly show that improvement of irrigation practices can widely compensate for such losses on a sustainable basis. Integration with rainwater management can even achieve a 10% global net gain. Such management interventions are highlighted to act as a pivotal target in supporting the implementation of the ambitious and seemingly conflicting SDG agenda.

  14. Granulocyte-Colony Stimulating Factor Increases Cerebral Blood Flow via a NO Surge Mediated by Akt/eNOS Pathway to Reduce Ischemic Injury

    Directory of Open Access Journals (Sweden)

    Hock-Kean Liew

    2015-01-01

    Full Text Available Granulocyte-colony stimulating factor (G-CSF protects brain from ischemic/reperfusion (I/R injury, and inhibition of nitric oxide (NO synthases partially reduces G-CSF protection. We thus further investigated the effects of G-CSF on ischemia-induced NO production and its consequence on regional cerebral blood flow (rCBF and neurological deficit. Endothelin-1 (ET-1 microinfused above middle cerebral artery caused a rapid reduction of rCBF (ischemia which lasted for 30 minutes and was followed by a gradual recovery of blood flow (reperfusion within the striatal region. Regional NO concentration increased rapidly (NO surge during ischemia and recovered soon to the baseline. G-CSF increased rCBF resulting in shorter ischemic duration and an earlier onset of reperfusion. The enhancement of the ischemia-induced NO by G-CSF accompanied by elevation of phospho-Akt and phospho-eNOS was noted, suggesting an activation of Akt/eNOS. I/R-induced infarct volume and neurological deficits were also reduced by G-CSF treatment. Inhibition of NO synthesis by L-NG-Nitroarginine Methyl Ester (L-NAME significantly reduced the effects of G-CSF on rCBF, NO surge, infarct volume, and neurological deficits. We conclude that G-CSF increases rCBF through a NO surge mediated by Akt/eNOS, which partially contributes to the beneficial effect of G-CSF on brain I/R injury.

  15. Validation of a surge model by full scale testing

    NARCIS (Netherlands)

    Slot, H.J.; Meulendijks, D.; Smeulers, J.P.M.

    2009-01-01

    Surge of turbo compressors can cause large stepwise changes in flow and pressure, which can potentially damage the compressor and any equipment that is in direct connection with the compressor. Surge is usually avoided by an anti surge controller (ASC). However, in spite of the ASC surge cycles may

  16. Validation of a surge model by full scale testing

    NARCIS (Netherlands)

    Smeulers, J.P.M.; Slot, H.J.; Meulendijks, D.

    2011-01-01

    Surge of turbo compressors can cause large stepwise changes in flow and pressure, which can potentially damage the compressor and any equipment that is in direct connection with the compressor. Surge is usually avoided by an anti surge controller (ASC). However, in spite of the ASC surge cycles may

  17. New piecewise-continuous hydraulic functions for modeling preferential flow in an intermittent-flood-irrigated field

    Science.gov (United States)

    Mohanty, B. P.; Bowman, R. S.; Hendrickx, J. M. H.; van Genuchten, M. T.

    Modeling water flow in macroporous field soils near saturation has been a major challenge in vadose zone hydrology. Using in situ and laboratory measurements, we developed new piecewise-continuous soil water retention and hydraulic conductivity functions to describe preferential flow in tile drains under a flood-irrigated agricultural field in Las Nutrias, New Mexico. After incorporation into a two-dimensional numerical flow code, CHAIN_2D, the performance of the new piecewise-continuous hydraulic functions was compared with that of the unimodal van Genuchten-Mualem model and with measured tile-flow data at the field site during a number of irrigation events. Model parameters were collected/estimated by site characterization (e.g., soil texture, surface/subsurface saturated/unsaturated soil hydraulic property measurements), as well as by local and regional-scale hydrologic monitoring (including the use of groundwater monitoring wells, piezometers, and different surface-irrigation and subsurface-drainage measurement systems). Comparison of numerical simulation results with the observed tile flow indicated that the new piecewise-continuous hydraulic functions generally predicted preferential flow in the tile drain reasonably well following all irrigation events at the field site. Also, the new bimodal soil water retention and hydraulic conductivity functions performed better than the unimodal van Genuchten-Mualem functions in terms of describing the observed flow regime at the field site.

  18. Preferential flow effects on transport and fate of chemicals and microorganisms in soils irrigated with wastewater

    Science.gov (United States)

    Puddu, Rita; Corrias, Roberto; Dessena, Maria Antonietta; Ferralis, Marcella; Marras, Gabriele; Pin, Paola; Spanu, Paola

    2010-05-01

    This work is part of a multidisciplinary research properly planned by the ENAS (Cagliari-Sardinia-Italy) to verify the consequences of urban wastewater reuse in irrigation practices on chemical, biological and hydrological behavior of agricultural soils of the Had as Soualem area (Morocco). The area consists of Fluventic Haploxerept soils, according to USDA Soil Taxonomy. Undisturbed large soil columns, 70 cm height and 20 cm diameter, were collected from plots, the locations of which were preliminarily individuated through a prior pedological study. The soils are characterized by an apparent structure, suggesting that preferential flow processes may occur in the study area, which may impact usable groundwater at depth. Wastewater reuse for irrigation simultaneously solves water shortage and wastewater disposal problems. Unfortunately, wastewaters generally contain high concentrations of suspended and dissolved solids, both organic and inorganic, and microbial contaminants (virus and bacteria) added to wastewater during domestic and industrial usage. Most of these contaminants are only partially removed during conventional sewage treatment so they remain in the irrigation water. Although adsorbing ions and microbes are relatively immobile within porous media, preferential flow and adsorption to mobile colloids can enhance their transport. There is limited knowledge regarding the role of preferential flow and colloidal transport on adsorbing contaminants. The main aim of this research is to determine the influence of preferential flow and colloids on wastewater contaminant transport. Leaching rates and arrival time of wastewater contaminants will be determined using field and laboratory measurements at the study sites in combination with preferential flow numerical modeling. To achieve these objectives the soil columns were analyzed for physical, chemical, and microbial characterization. At the laboratory, an experimental facility was set up and sensors for

  19. Ensemble forecasting of short-term system scale irrigation demands using real-time flow data and numerical weather predictions

    Science.gov (United States)

    Perera, Kushan C.; Western, Andrew W.; Robertson, David E.; George, Biju; Nawarathna, Bandara

    2016-06-01

    Irrigation demands fluctuate in response to weather variations and a range of irrigation management decisions, which creates challenges for water supply system operators. This paper develops a method for real-time ensemble forecasting of irrigation demand and applies it to irrigation command areas of various sizes for lead times of 1 to 5 days. The ensemble forecasts are based on a deterministic time series model coupled with ensemble representations of the various inputs to that model. Forecast inputs include past flow, precipitation, and potential evapotranspiration. These inputs are variously derived from flow observations from a modernized irrigation delivery system; short-term weather forecasts derived from numerical weather prediction models and observed weather data available from automatic weather stations. The predictive performance for the ensemble spread of irrigation demand was quantified using rank histograms, the mean continuous rank probability score (CRPS), the mean CRPS reliability and the temporal mean of the ensemble root mean squared error (MRMSE). The mean forecast was evaluated using root mean squared error (RMSE), Nash-Sutcliffe model efficiency (NSE) and bias. The NSE values for evaluation periods ranged between 0.96 (1 day lead time, whole study area) and 0.42 (5 days lead time, smallest command area). Rank histograms and comparison of MRMSE, mean CRPS, mean CRPS reliability and RMSE indicated that the ensemble spread is generally a reliable representation of the forecast uncertainty for short lead times but underestimates the uncertainty for long lead times.

  20. Global Change and Human Consumption of Freshwater Driven by Flow Regulation and Irrigation

    Science.gov (United States)

    Jaramillo, F.; Destouni, G.

    2015-12-01

    Recent studies show major uncertainties about the magnitude and key drivers of global freshwater change, historically and projected for the future. The tackling of these uncertainties should be a societal priority to understand: 1) the role of human change drivers for freshwater availability changes, 2) the global water footprint of humanity and 3) the relation of human freshwater consumption to a proposed planetary boundary. This study analyses worldwide hydroclimatic changes, as observed during 1900-2009 in 99 large hydrological basins across all continents. We test whether global freshwater change may be driven by major developments of flow regulation and irrigation (FRI) occurring over this period. Independent categorization of the variability of FRI-impact strength among the studied basins is used to identify statistical basin differences in occurrence and strength of characteristic hydroclimatic signals of FRI. Our results show dominant signals of increasing relative evapotranspiration in basins affected by flow regulation and/or irrigation, in conjunction with decreasing relative intra-annual variability of runoff in basins affected by flow regulation. The FRI-related increase in relative evapotranspiration implies an increase of 4,688 km3/yr in global annual average water flow from land to the atmosphere. This observation-based estimate extends considerably the upper quantification limits of both FRI-driven and total global human consumption of freshwater, as well as the global water footprint of humanity. Our worldwide analysis shows clear FRI-related change signals emerging directly from observations, in spite of large change variability among basins and many other coexisting change drivers in both the atmosphere and the landscape. These results highlight the importance of considering local water use as a key change driver in Earth system studies and modelling, of relevance for global change and human consumption of freshwater.

  1. Svalbard surging glacier landsystems

    Science.gov (United States)

    Lovell, Harold; Benn, Douglas; Lukas, Sven; Flink, Anne

    2014-05-01

    The percentage of Svalbard glaciers thought to be of surge-type is somewhere between 13-90% according to different sources variously based on statistical analysis and observations of diagnostic glaciological and geomorphological features, e.g. looped moraines. Developing a better understanding of which of these figures, if either, is most realistic is important in the context of glacier dynamics and related contributions of small glaciers and ice caps to sea level change in the immediate future. We present detailed geomorphological assessments of the margins of several known surge-type glaciers in Svalbard in order to update and improve the existing framework by which they are identified, and to provide a foundation for future reassessments of the surge-type glacier population based on distinct landform-sediment assemblages. Three landsystems are proposed: (1) Surges of small valley glaciers produce a prominent ice-cored latero-frontal moraine at their surge maximum and are characterised by an inner zone of ice stagnation terrain (hummocky topography, kettle lakes, debris flows) with no or only very few poorly-defined bedforms (crevasse squeeze ridges, eskers and flutes) and no recessional moraines. Many of these glaciers may have surged in the past but show no signs that they have the capability to do so again in the future. (2) Larger land-terminating glaciers, often with several tributaries, typically produce a push moraine complex which contains evidence for multiple advances, as identified from ridge-meltwater channel relationships. The inner zone often contains a large lagoon, partly dammed by the push moraine complex, and widespread ice stagnation terrain. Crevasse squeeze ridges, eskers and flutes are well-defined but small and limited in number and distribution. (3) Surges of large tidewater glaciers produce distinctive, often multi-generational, landform assemblages both in submarine and lateral terrestrial positions. The well-preserved submarine record

  2. Calibrating a flow model in an irrigation network: Case study in Alicante, Spain

    Directory of Open Access Journals (Sweden)

    Modesto Pérez-Sánchez

    2017-04-01

    Full Text Available The usefulness of models depends on their validation in a calibration process, ensuring that simulated flows and pressure values in any line are really occurring and, therefore, becoming a powerful decision tool for many aspects in the network management (i.e., selection of hydraulic machines in pumped systems, reduction of the installed power in operation, analysis of theoretical energy recovery. A new proposed method to assign consumptions patterns and to determine flows over time in irrigation networks is calibrated in the present research. As novelty, the present paper proposes a robust calibration strategy for flow assignment in lines, based on some key performance indicators (KPIF coming from traditional hydrological models: Nash-Sutcliffe coefficient (non-dimensional index, root relative square error (error index and percent bias (tendency index. The proposed strategy for calibration was applied to a real case in Alicante (Spain, with a goodness of fit considered as “very good” in many indicators. KPIF parameters observed present a satisfactory goodness of fit of the series, considering their repeatability. Average Nash-Sutcliffe coefficient value oscillated between 0.30 and 0.63, average percent bias values were below 10% in all the range, and average root relative square error values varied between 0.65 and 0.80.

  3. Modeling and Controlling Flow Transient in Pipeline Systems: Applied for Reservoir and Pump Systems Combined with Simple Surge Tank

    Directory of Open Access Journals (Sweden)

    Itissam ABUIZIAH

    2014-03-01

    Full Text Available When transient conditions (water hammer exist, the life expectancy of the system can be adversely impacted, resulting in pump and valve failures and catastrophic pipe rupture. Hence, transient control has become an essential requirement for ensuring safe operation of water pipeline systems. To protect the pipeline systems from transient effects, an accurate analysis and suitable protection devices should be used. This paper presents the problem of modeling and simulation of transient phenomena in hydraulic systems based on the characteristics method. Also, it provides the influence of using the protection devices to control the adverse effects due to excessive and low pressure occuring in the transient. We applied this model for two main pipeline systems: Valve and pump combined with a simple surge tank connected to reservoir. The results obtained by using this model indicate that the model is an efficient tool for water hammer analysis. Moreover, using a simple surge tank reduces the unfavorable effects of transients by reducing pressure fluctuations.

  4. Evaluation of diffuse and preferential flow pathways of infiltrated precipitation and irrigation using oxygen and hydrogen isotopes

    Science.gov (United States)

    Ma, Bin; Liang, Xing; Liu, Shaohua; Jin, Menggui; Nimmo, John R.; Li, Jing

    2017-01-01

    Subsurface-water flow pathways in three different land-use areas (non-irrigated grassland, poplar forest, and irrigated arable land) in the central North China Plain were investigated using oxygen (18O) and hydrogen (2H) isotopes in samples of precipitation, soils, and groundwater. Soil water in the top 10 cm was significantly affected by both evaporation and infiltration. Water at 10-40 cm depth in the grassland and arable land, and 10-60 cm in poplar forest, showed a relatively short residence time, as a substantial proportion of antecedent soil water was mixed with a 92-mm storm infiltration event, whereas below those depths (down to 150 cm), depleted δ18O spikes suggested that some storm water bypassed the shallow soil layers. Significant differences, in soil-water content and δ18O values, within a small area, suggested that the proportion of immobile soil water and water flowing in subsurface pathways varies depending on local vegetation cover, soil characteristics and irrigation applications. Soil-water δ18O values revealed that preferential flow and diffuse flow coexist. Preferential flow was active within the root zone, independent of antecedent soil-water content, in both poplar forest and arable land, whereas diffuse flow was observed in grassland. The depleted δ18O spikes at 20-50 cm depth in the arable land suggested the infiltration of irrigation water during the dry season. Temporal isotopic variations in precipitation were subdued in the shallow groundwater, suggesting more complete mixing of different input waters in the unsaturated zone before reaching the shallow groundwater.

  5. Water budget and simulation of one-dimensional unsaturated flow for a flood- and a sprinkler-irrigated field near Milford, Utah

    Science.gov (United States)

    Susong, David D.

    1995-01-01

    Ground-water recharge to basin-fill aquifers from unconsumed irrigation water in the western United States is being reduced as irrigators convert to more efficient irrigation systems. In some areas, these changes in irrigation methods may be contributing to ground-water-level declines and reducing the quantity of water available to downgradient users. The components of the water budget were measured or calculated for each field for the 1992 and 1993 irrigation seasons. Precipitation was about 6.5 cm (2.6 inches) both years. The flood-irrigated field received 182 and 156 centimeters (71.6 and 61.4 inches) of irrigation water in 1992 and 1993, and the sprinkler-irrigated field received 52.8 and 87.2 centimeters (20.8 and 34.3 inches) of water, respectively. Evapotranspiration for alfalfa was calculated using the Penman-Monteith combination equation and was 95.4 and 84.3 centimeters (37.2 and 33.2 inches) for 1992 and 1993, respectively. No runoff and no significant change in soil moisture in storage was observed from either field. Recharge to the aquifer from the flood-irrigated field was 93.3 and 78.1 centimeters (36.7 and 30.7 inches) in 1992 and 1993 and from the sprinkler-irrigated field was -35.9 and 9.3 centimeters (-14.1 and 3.7 inches), respectively. The daily water budget and soil-moisture profiles in the upper 6.4 meters (21 feet) of the unsaturated zone were simulated with an unsaturated flow model for average climate conditions. Simulated recharge was 57.4 and 50.5 percent of the quantity of irrigation water applied to the flood-irrigated field during 1992 and 1993, respectively, and was 8.7 and 13.8 percent of the quantity of irrigation water applied to the sprinkler- irrigated field.

  6. Behaviour of a small sedimentary volcanic aquifer receiving irrigation return flows: La Aldea, Gran Canaria, Canary Islands (Spain)

    Science.gov (United States)

    Cruz-Fuentes, T.; Heredia, J.; Cabrera, M. C.; Custodio, E.

    2014-06-01

    In many arid and semi-arid areas, intensive cultivation is practiced despite water commonly being a limiting factor. Often, irrigation water is from local aquifers or imported from out-of-area aquifers and surface reservoirs. Irrigation return flows become a significant local recharge source, but they may deteriorate aquifer water quality. La Aldea valley, located in the western sector of Gran Canaria Island (Atlantic Ocean), is a coastal, half-closed depression in altered, low-permeability volcanics with alluvium in the gullies and scree deposits over a large part of the area. This area is intensively cultivated. Irrigation water comes from reservoirs upstream and is supplemented (average 30 %) by local groundwater; supplementation goes up to 70 % in dry years, in which groundwater reserves are used up to exhaustion if the dry period persists. Thus, La Aldea aquifer is key to the water-supply system, whose recharge is mostly from return irrigation flows and the scarce local rainfall recharge on the scree formations, conveyed to the gully deposits. To quantify the hydrogeological conceptual model and check data coherence, a simplified numerical model has been constructed, which can be used as a tool to help in water management.

  7. The Effect of Needle-insertion Depth on the Irrigant Flow in the Root Canal : Evaluation Using an Unsteady Computational Fluid Dynamics Model

    NARCIS (Netherlands)

    Boutsioukis, Christos; Lambrianidis, Theodor; Verhaagen, Bram; Versluis, Michel; Kastrinakis, Eleftherios; Wesselink, Paul R.; van der Sluis, Lucas W. M.

    2010-01-01

    Introduction: The aim of this study was to evaluate the effect of needle-insertion depth on the irrigant flow inside a prepared root canal during final irrigation with a syringe and two different needle types using a Computational Fluid Dynamics (CFD) model. Methods: A validated CFD model was used t

  8. The effect of needle-insertion depth on the irrigant flow in the root canal: evaluation using an unsteady computational fluid dynamics model

    NARCIS (Netherlands)

    Boutsioukis, C.; Lambrianidis, T.; Verhaagen, B.; Versluis, M.; Kastrinakis, E.; Wesselink, P.R.; van der Sluis, L.W.M.

    2010-01-01

    Introduction The aim of this study was to evaluate the effect of needle-insertion depth on the irrigant flow inside a prepared root canal during final irrigation with a syringe and two different needle types using a Computational Fluid Dynamics (CFD) model. Methods A validated CFD model was used to

  9. Laser-activated irrigation within root canals: cleaning efficacy and flow visualization

    NARCIS (Netherlands)

    Groot, de S.D.; Verhaagen, B.; Versluis, M.; Wu, M.-K.; Wesselink, P.R.; Sluis, van der L.W.M.

    2009-01-01

    Aim: To test ex vivo the efficiency of laser-activated irrigation in removing dentine debris from the apical part of the root canal and to visualize in vitro the fluid dynamics during the activation of the irrigant by laser, using high-speed imaging at a relevant timescale. - Methodology: Root cana

  10. Laser-activated irrigation within root canals: cleaning efficacy and flow visualization

    NARCIS (Netherlands)

    de Groot, S.D.; Verhaagen, B.; Versluis, M.; Wu, M.K.; Wesselink, P.R.; van der Sluis, L.W.M.

    2009-01-01

    Aim  To test ex vivo the efficiency of laser-activated irrigation in removing dentine debris from the apical part of the root canal and to visualize in vitro the fluid dynamics during the activation of the irrigant by laser, using high-speed imaging at a relevant timescale. Methodology  Root canals

  11. Laser-activated irrigation within root canals : cleaning efficacy and flow visualization

    NARCIS (Netherlands)

    de Groot, S. D.; Verhaagen, B.; Versluis, M.; Wu, M. -K.; Wesselink, P. R.; van der Sluis, L. W. M.

    2009-01-01

    P>Aim To test ex vivo the efficiency of laser-activated irrigation in removing dentine debris from the apical part of the root canal and to visualize in vitro the fluid dynamics during the activation of the irrigant by laser, using high-speed imaging at a relevant timescale. Methodology Root canals

  12. Appraising options to reduce shallow groundwater tables and enhance flow conditions over regional scales in an irrigated alluvial aquifer system

    Science.gov (United States)

    Morway, Eric D.; Gates, Timothy K.; Niswonger, Richard G.

    2013-01-01

    Some of the world’s key agricultural production systems face big challenges to both water quantity and quality due to shallow groundwater that results from long-term intensive irrigation, namely waterlogging and salinity, water losses, and environmental problems. This paper focuses on water quantity issues, presenting finite-difference groundwater models developed to describe shallow water table levels, non-beneficial groundwater consumptive use, and return flows to streams across two regions within an irrigated alluvial river valley in southeastern Colorado, USA. The models are calibrated and applied to simulate current baseline conditions in the alluvial aquifer system and to examine actions for potentially improving these conditions. The models provide a detailed description of regional-scale subsurface unsaturated and saturated flow processes, thereby enabling detailed spatiotemporal description of groundwater levels, recharge to infiltration ratios, partitioning of ET originating from the unsaturated and saturated zones, and groundwater flows, among other variables. Hybrid automated and manual calibration of the models is achieved using extensive observations of groundwater hydraulic head, groundwater return flow to streams, aquifer stratigraphy, canal seepage, total evapotranspiration, the portion of evapotranspiration supplied by upflux from the shallow water table, and irrigation flows. Baseline results from the two regional-scale models are compared to model predictions under variations of four alternative management schemes: (1) reduced seepage from earthen canals, (2) reduced irrigation applications, (3) rotational lease fallowing (irrigation water leased to municipalities, resulting in temporary dry-up of fields), and (4) combinations of these. The potential for increasing the average water table depth by up to 1.1 and 0.7 m in the two respective modeled regions, thereby reducing the threat of waterlogging and lowering non-beneficial consumptive use

  13. Impact of irrigation flow rate and intrapericardial fluid on cooled-tip epicardial radiofrequency ablation.

    Science.gov (United States)

    Aryana, Arash; O'Neill, Padraig Gearoid; Pujara, Deep K; Singh, Steve K; Bowers, Mark R; Allen, Shelley L; d'Avila, André

    2016-08-01

    The optimal irrigation flow rate (IFR) during epicardial radiofrequency (RF) ablation has not been established. This study specifically examined the impact of IFR and intrapericardial fluid (IPF) accumulation during epicardial RF ablation. Altogether, 452 ex vivo RF applications (10 g for 60 seconds) delivered to the epicardial surface of bovine myocardium using 3 open-irrigated ablation catheters (ThermoCool SmartTouch, ThermoCool SmartTouch-SF, and FlexAbility) and 50 in vivo RF applications delivered (ThermoCool SmartTouch-SF) in 4 healthy adult swine in the presence or absence of IPF were examined. Ex vivo, RF was delivered at low (≤3 mL/min), reduced (5-7 mL/min), and high (≥10 mL/min) IFRs using intermediate (25-35 W) and high (35-45 W) power. In vivo, applications were delivered (at 9.3 ± 2.2 g for 60 seconds at 39 W) using reduced (5 mL/min) and high (15 mL/min) IFRs. Ex vivo, surface lesion diameter inversely correlated with IFR, whereas maximum lesion diameter and depth did not differ. While steam pops occurred more frequently at low IFR using high power (ThermoCool SmartTouch and ThermoCool SmartTouch-SF), tissue disruption was rare and did not vary with IFR. In vivo, charring/steam pop was not detected. Although there were no discernible differences in lesion size with IFR, surface lesion diameter, maximum diameter, depth, and volume were all smaller in the presence of IPF at both IFRs. Cooled-tip epicardial RF ablation created using reduced IFRs (5-7 mL/min) yields lesion sizes similar to those created using high IFRs (≥10 mL/min) without an increase in steam pop/tissue disruption, whereas the presence of IPF significantly reduces the lesion size. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  14. Environmental impact of irrigation with greywater treated by recirculating vertical flow constructed wetlands in two climatic regions.

    Science.gov (United States)

    Gross, Amit; Alfiya, Yuval; Sklarz, Menachem; Maimon, Adi; Friedler, Eran

    2014-01-01

    Reuse of greywater (GW) has raised environmental and public health concerns. Specifically, these concerns relate to onsite treatment operated by non-professionals; systems must therefore be reliable, simple to use and also economically feasible if they are to be widely used. The aims of this study were to: (a) investigate GW treatment efficiency using 20 full-scale recirculating vertical flow constructed wetlands (RVFCWs) operated in households in arid and Mediterranean regions; and (b) study the long-term effects of irrigation with treated GW on soil properties. RVFCW systems were installed and monitored routinely over 3 years. Raw, treated and disinfected treated GW samples were analyzed for various physicochemical and microbial parameters. Native soil plots and nearby freshwater (FW) and treated GW irrigated soil plots were sampled twice a year - at the end of the winter and at the end of the summer. Soil samples were analyzed for various physicochemical and microbial parameters. Overall, the RVFCW proved to be a robust and reliable GW treatment system. The treated GW quality met strict Israeli regulations for urban irrigation. Results also suggest that irrigation with sufficiently treated GW has no adverse effects on soil properties. Yet, continued monitoring to follow longer term trends is recommended.

  15. Measurement of the filling height of transient two-phase surge flows in pipelines by means of electronics; Messung der Fuellhoehe von transienten Zweiphasenschwallstroemungen in Rohrleitungen mittels Ultraschall

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, B.; Rockstroh, M. [Technische Univ. Dresden (Germany). Inst. fuer Energiemaschinen und Maschinenlabor

    1997-12-01

    The aim of the ultrasonic measurements was the determination of the time course of the level of a transient surge flow with swirl and waves in partly filled roughly horizontally laid pipelines. The running time of the ultrasonic waves from the test head to the liquid surface and back was measured for this purpose. The course of the stress was recorded digitally and was evaluated with the aid of software. Waves, swirl, turbulence of flow and introduced test bodies in the flow caused typical echoes, which had to be taken into account in the evaluation. As the test head was fitted on the outside of the pipe (clamp-on technique), the pipe wall thickness and the speed of sound in the pipe wall had to be included in the calculation of filling height by means of a correction. [Deutsch] Ziel der Ultraschallmessungen war die Bestimmung des zeitlichen Verlaufes der Fuellhoehe einer transienten, drall- und wellenbehafteten Schwallstroemung in teilgefuellten, etwa horizontal verlegten Rohrleitungen. Hierzu wurde die Laufzeit der Ultraschallwellen vom Pruefkopf zur Fluessigkeitsoberflaeche und zurueck gemessen. Die Laufzeit der Ultraschallwellen wurde auf eine quasi-analog elektrische Spannung abgebildet. Der Spannungsverlauf wurde digital aufgezeichnet und softwaregestuetzt ausgewertet. Wellen, Drall, Stroemungsturbulenzen sowie eingebrachte Pruefkoerper in der Stroemung hatten typische Echoerscheinungen zur Folge, die bei der Auswertung zu beruecksichtigen waren. Da der Pruefkopf aussen am Rohr angebracht war (clamp-on-Technik), musste die Rohrwandstaerke und die Schallgeschwindigkeit in der Rohrwandung mittels eines Korrekturgliedes in die Fuellhoehenberechnung eingezogen werden. (orig.)

  16. Validation of a surge model by full scale testing

    NARCIS (Netherlands)

    Smeulers, J.P.M.; Gonzalez Díez, N.; Slot, H.J.

    2012-01-01

    Surge of turbo compressors can cause large almost step like changes in flow and pressure, which can potentially damage the compressor and any equipment that is in direct connection with the compressor. In spite of an anti-surge controller (ASC), at extreme events surge cycles may occur. In order to

  17. Influence of irrigation on the level, salinity and flow of groundwater at ...

    African Journals Online (AJOL)

    2010-03-31

    Mar 31, 2010 ... Suitable internal subsurface drainage should be cleaned, ... Keywords: Drainage, irrigation and scheduling, soil water quality, water and salt balance ..... groundwater was pumped or bailed out of the piezometers and.

  18. Draft tube discharge fluctuation during self-sustained pressure surge: fluorescent particle image velocimetry in two-phase flow

    Science.gov (United States)

    Müller, A.; Dreyer, M.; Andreini, N.; Avellan, F.

    2013-04-01

    Hydraulic machines play an increasingly important role in providing a secondary energy reserve for the integration of renewable energy sources in the existing power grid. This requires a significant extension of their usual operating range, involving the presence of cavitating flow regimes in the draft tube. At overload conditions, the self-sustained oscillation of a large cavity at the runner outlet, called vortex rope, generates violent periodic pressure pulsations. In an effort to better understand the nature of this unstable behavior and its interaction with the surrounding hydraulic and mechanical system, the flow leaving the runner is investigated by means of particle image velocimetry. The measurements are performed in the draft tube cone of a reduced scale model of a Francis turbine. A cost-effective method for the in-house production of fluorescent seeding material is developed and described, based on off-the-shelf polyamide particles and Rhodamine B dye. Velocity profiles are obtained at three streamwise positions in the draft tube cone, and the corresponding discharge variation in presence of the vortex rope is calculated. The results suggest that 5-10 % of the discharge in the draft tube cone is passing inside the vortex rope.

  19. Climate change and environmental water reallocation in the Murray-Darling Basin: Impacts on flows, diversions and economic returns to irrigation

    Science.gov (United States)

    Kirby, J. M.; Connor, J.; Ahmad, M. D.; Gao, L.; Mainuddin, M.

    2014-10-01

    Increasing river environment degradation from historical growth in withdrawal is leading to reallocation of water from irrigation in many basins. We examine how potential reduction in irrigation allocations under a newly enacted environmental water plan for the Murray Darling Basin in Australia, in combination with projected climate change, impact on flows, diversions and the economic returns to irrigation. We use an integrated hydrology-economics model capable of simulating the year-to-year variability of flows, diversions, and economic returns to model three levels of reallocation (2400, 2750 and 3200 GL) under the historical climate, and under a dry, a median and a wet climate change projection. Previous assessments of the reallocation plan do not address climate change impacts, nor the impact of year to year variability in flows on economic returns. The broad results of this analysis are that estimated river flows and diversions are more sensitive to the range of climate change projections than to the range of diversion reallocation scenarios considered. The projected median climate change more or less removes from flows the gains to the environment resulting from reallocation. Reallocations only in combination with no climate change, or climate change at the wetter end of the range of projections, will lead to flows greater than those experienced under the water management regime prior to reallocation. The reduction in economic returns to irrigation is less than the reduction in water available for irrigation: a 25% reduction in the annual average water availability is estimated to reduce the annual average gross value of irrigated agricultural production by about 10%. This is consistent with expectation of economic theory (since more marginal activities are reduced first) and also with observations of reduced water availability and returns in the recent drought in the Murray-Darling Basin. Irrigation returns vary less across the range of climate change

  20. Surge Driven Return Flow Results in Deposition of Coarse Grain Horizons Archiving a 4000 Year Record of Extreme Storm Events, Cape Cod, Massachusetts

    Science.gov (United States)

    Maio, C. V.; Donnelly, J. P.; Sullivan, R.; Weidman, C. R.; Sheremet, V.

    2014-12-01

    The brevity of the instrumental record and lack of detailed historical accounts is a limiting factor in our understanding of the relationship between climate change and the frequency and intensity of extreme storm events. This study applied paleotempestologic and hydrographic methods to identify the mechanisms of storm-induced coarse grain deposition and reconstruct a late Holocene storm record within Waquoit Bay, Massachusetts. Three sediment cores (6.0 m, 8.4 m, and 8.2 m) were collected in 3 m of water using a vibracore system. Grain sizes were measured along core to identify coarse grain anomalies that serve as a proxy for past storm events. An historical age model (1620-2011 AD) was developed based on Pb pollution chronomarkers derived from X-Ray Florescence bulk Pb data, equating to a sedimentation rate of 8-8.3 mm/yr (R2 = 0.99). A long-term (4000 to 275 years before present) sedimentation rate of 1.1-1.4 mm/yr (R2 = 0.89) was calculated based on twenty-four continuous flow atomic mass spectrometry 14C ages of marine bivalves. To determine hydrographic conditions within the embayment during storm events current meters and tide gauges were deployed during Hurricane Irene (2011) which measured a storm surge of 88 cm above mean sea level. The buildup of storm water against the landward shoreline resulted in a measured 10 cm/s seaward moving bottom current capable of transporting coarse sand eroded from the adjacent shoreface into the coring site. Modeled surges for eleven modern and historic storm events ranged in height from 0.37 m (2011) to 3.72 m (1635) above mean high water. The WAQ1, WAQ2, and WAQ3 cores recorded a total of 89, 139, and 137 positive anomalies that exceeded the lower threshold and 15, 34, and 12 that exceeded the upper threshold respectively. Events recorded during the historic period coincide with documented storm events. The mean frequency within the three cores applying the lower threshold was 2.6 events per century, while applying the

  1. Emergency department surge capacity: recommendations of the Australasian Surge Strategy Working Group.

    Science.gov (United States)

    Bradt, David A; Aitken, Peter; Fitzgerald, Gerry; Swift, Roger; O'Reilly, Gerard; Bartley, Bruce

    2009-12-01

    For more than a decade, emergency medicine (EM) organizations have produced guidelines, training, and leadership for disaster management. However, to date there have been limited guidelines for emergency physicians (EPs) needing to provide a rapid response to a surge in demand. The aim of this project was to identify strategies that may guide surge management in the emergency department (ED). A working group of individuals experienced in disaster medicine from the Australasian College for Emergency Medicine Disaster Medicine Subcommittee (the Australasian Surge Strategy Working Group) was established to undertake this work. The Working Group used a modified Delphi technique to examine response actions in surge situations and identified underlying assumptions from disaster epidemiology and clinical practice. The group then characterized surge strategies from their corpus of experience; examined them through available relevant published literature; and collated these within domains of space, staff, supplies, and system operations. These recommendations detail 22 potential actions available to an EP working in the context of surge, along with detailed guidance on surge recognition, triage, patient flow through the ED, and clinical goals and practices. The article also identifies areas that merit future research, including the measurement of surge capacity, constraints to strategy implementation, validation of surge strategies, and measurement of strategy impacts on throughput, cost, and quality of care.

  2. Irrigant flow during photon-induced photoacoustic streaming (PIPS) using Particle Image Velocimetry (PIV).

    Science.gov (United States)

    Koch, Jon D; Jaramillo, David E; DiVito, Enrico; Peters, Ove A

    2016-03-01

    This study aimed to compare fluid movements generated from photon-induced photoacoustic streaming (PIPS) and passive ultrasonic irrigation (PUI). Particle Image Velocimetry (PIV) was performed using 6-μm melamine spheres in water. Measurement areas were 3-mm-long sections of the canal in the coronal, midroot and apical regions for PIPS (erbium/yttrium-aluminium garnet (Er:YAG) laser set at 15 Hz with 20 mJ), or passive ultrasonic irrigation (PUI, non-cutting insert at 30% unit power) was performed in simulated root canals prepared to an apical size #30/0.04 taper. Fluid movement was analysed directly subjacent to the apical ends of ultrasonic insert or fiber optic tips as well as at midroot and apically. During PUI, measured average velocities were around 0.03 m/s in the immediate vicinity of the sides and tip of the ultrasonic file. Speeds decayed to non-measureable values at a distance of about 2 mm from the sides and tip. During PIPS, typical average speeds were about ten times higher than those measured for PUI, and they were measured throughout the length of the canal, at distances up to 20 mm away. PIPS caused higher average fluid speeds when compared to PUI, both close and distant from the instrument. The findings of this study could be relevant to the debriding and disinfecting stage of endodontic therapy. Irrigation enhancement beyond needle irrigation is relevant to more effectively eradicate microorganisms from root canal systems. PIPS may be an alternative approach due to its ability to create high streaming velocities further away from the activation source compared to ultrasonic activation.

  3. The soil-water flow system beneath a cotton field in arid north-west China, serviced by mulched drip irrigation using brackish water

    Science.gov (United States)

    Li, Xianwen; Jin, Menggui; Huang, Jinou; Yuan, Jingjing

    2015-02-01

    A field experiment was carried out in southern Xinjiang, China, to reveal soil-water flow pattern beneath a combined plastic-mulch (film) and drip-irrigation system using brackish water. The soil-water flow system (SWFS) was characterized from soil surface to the water table based on observed spatio-temporal distribution of total soil-water potential, water content and electric conductivity. Root suction provided a strong inner sink. The results indicated that SWFS determined the soil salinity and moisture distribution. Drip-irrigation events could leach excess salts from the root zone and provide soil conditions with a tolerable salinity level that supports the growth of cotton. High-salinity strips were formed along the wetting front and at the bare soil surface. Hydrogeology conditions, irrigation regime, climate, plant growth and use of mulch would affect potential sources and sinks, boundary conditions and the size of the SWFS. At depth 0-60 cm, the soil salinity at the end of the irrigation season was 1.9 times that at the beginning. Beneath the mulch cover, the soil-water content in the `wide rows' zone (55 cm between the two rows with no drip line) was higher than that in the `narrow rows' zone (15 cm between the two rows with a drip line) due to the strong root-water uptake. The downward water flow below the divergent curved surface of zero flux before irrigation, and the water-table fluctuation with irrigation events, indicated that excessive irrigation occurred.

  4. THEORETICAL FLOW MODEL THROUGH A CENTRIFUGAL PUMP USED FOR WATER SUPPLY IN AGRICULTURE IRRIGATION

    Directory of Open Access Journals (Sweden)

    SCHEAUA Fanel Dorel

    2017-05-01

    motion of the rotor. A theoretical model for calculating the flow of the working fluid through the interior of a centrifugal pump model is presented in this paper as well as the numerical analysis on the virtual model performed with the ANSYS CFX software in order to highlight the flow parameters and flow path-lines that are formed during centrifugal pump operation.

  5. Irrigant Flow beyond the Insertion Depth of an Ultrasonically Oscillating File in Straight and Curved Root Canals : Visualization and Cleaning Efficacy

    NARCIS (Netherlands)

    Malki, Maher; Verhaagen, Bram; Jiang, Lei-Meng; Nehme, Walid; Naaman, Alfred; Versluis, Michel; Wesselink, Paul; van der Sluis, Lucas

    2012-01-01

    Introduction: The purpose of this study was to evaluate the influence of the insertion depth of an ultrasonically oscillating file on the ability to remove dentin debris from simulated canal irregularities in an extracted tooth model of a straight root canal and its influence on the flow of irrigant

  6. Positive feedback stabilization of centrifugal compressor surge

    NARCIS (Netherlands)

    Willems, Frank; Heemels, W.P.M.H.; de Jager, Bram; Stoorvogel, Antonie Arij

    2002-01-01

    Stable operation of axial and centrifugal compressors is limited towards low mass flows due to the occurrence of surge. The stable operating region can be enlarged by active control. In this study, we use a control valve which is fully closed in the desired operating point and only opens to stabiliz

  7. Positive feedback stabilization of centrifugal compressor surge

    NARCIS (Netherlands)

    Willems, Frank; Heemels, W.P.M.H.; de Jager, Bram; Stoorvogel, Antonie Arij

    Stable operation of axial and centrifugal compressors is limited towards low mass flows due to the occurrence of surge. The stable operating region can be enlarged by active control. In this study, we use a control valve which is fully closed in the desired operating point and only opens to

  8. Computer-assisted mapping of pyroclastic surges.

    Science.gov (United States)

    Malin, M C; Sheridan, M F

    1982-08-13

    Volcanic hazard maps of surge boundaries and deposit thickness can be created by using a simplified eruption model based on an "energy line" concept of pyroclastic surge and flow emplacement. Computer image-processing techniques may be used to combine three-dimensional representations of the energy relations of pyroclasts moving under the influence of gravity (defined by an "energy cone") with digital topographic models of volcanoes to generate theoretical hazard maps. The deposit boundary and thickness calculated for the 18 May 1980 eruption of Mount St. Helens are qualitatively similar to those actually observed.

  9. Deep FIFO Surge Buffer

    Science.gov (United States)

    Temple, Gerald; Siegel, Marc; Amitai, Zwie

    1991-01-01

    First-in/first-out (FIFO) temporarily stores short surges of data generated by data-acquisition system at excessively high rate and releases data at lower rate suitable for processing by computer. Size and complexity reduced while capacity enhanced by use of newly developed, sophisticated integrated circuits and by "byte-folding" scheme doubling effective depth and data rate.

  10. Deep FIFO Surge Buffer

    Science.gov (United States)

    Temple, Gerald; Siegel, Marc; Amitai, Zwie

    1991-01-01

    First-in/first-out (FIFO) temporarily stores short surges of data generated by data-acquisition system at excessively high rate and releases data at lower rate suitable for processing by computer. Size and complexity reduced while capacity enhanced by use of newly developed, sophisticated integrated circuits and by "byte-folding" scheme doubling effective depth and data rate.

  11. Irrigant flow beyond the insertion depth of an ultrasonically oscillating file in straight and curved root canals: visualization and cleaning efficacy.

    Science.gov (United States)

    Malki, Maher; Verhaagen, Bram; Jiang, Lei-Meng; Nehme, Walid; Naaman, Alfred; Versluis, Michel; Wesselink, Paul; van der Sluis, Lucas

    2012-05-01

    The purpose of this study was to evaluate the influence of the insertion depth of an ultrasonically oscillating file on the ability to remove dentin debris from simulated canal irregularities in an extracted tooth model of a straight root canal and its influence on the flow of irrigant in both straight and curved canals. A tooth model with artificial depressions in 1 canal wall at 0.5, 2, 4, and 6 mm from the working length was used. Ultrasonic-activated irrigation was performed with the file inserted 1, 2, 3, 4, or 5 mm short of the working length. Dye penetration and high-speed recordings of the flow in straight and curved canals showed the static and dynamic behavior of the flow during ultrasonic activation. The overall cleaning efficacy decreased with increasing distance between the file and the apex, with the depressions next to the file and within 3 mm in front of the file being the cleanest. The flow observed from the visualization experiments matched this distance, suggesting a direct relation between flow and cleaning. The observed flow depth increased with increasing power setting; the curvature of the root canal had no influence on the flow depth. High-speed imaging showed a start-up phase with deeper fluid activation than in the steady phase afterward. The ultrasonically oscillating file could remove dentin debris up to 3 mm in front of the file tip, coinciding with the extent of the observed flow. The root canal curvature had no influence on the irrigant flow. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  12. Review: Regional groundwater flow modeling in heavily irrigated basins of selected states in the western United States

    Science.gov (United States)

    Rossman, Nathan R.; Zlotnik, Vitaly A.

    2013-09-01

    Water resources in agriculture-dominated basins of the arid western United States are stressed due to long-term impacts from pumping. A review of 88 regional groundwater-flow modeling applications from seven intensively irrigated western states (Arizona, California, Colorado, Idaho, Kansas, Nebraska and Texas) was conducted to provide hydrogeologists, modelers, water managers, and decision makers insight about past modeling studies that will aid future model development. Groundwater models were classified into three types: resource evaluation models (39 %), which quantify water budgets and act as preliminary models intended to be updated later, or constitute re-calibrations of older models; management/planning models (55 %), used to explore and identify management plans based on the response of the groundwater system to water-development or climate scenarios, sometimes under water-use constraints; and water rights models (7 %), used to make water administration decisions based on model output and to quantify water shortages incurred by water users or climate changes. Results for 27 model characteristics are summarized by state and model type, and important comparisons and contrasts are highlighted. Consideration of modeling uncertainty and the management focus toward sustainability, adaptive management and resilience are discussed, and future modeling recommendations, in light of the reviewed models and other published works, are presented.

  13. Demand surge following earthquakes

    Science.gov (United States)

    Olsen, Anna H.

    2012-01-01

    Demand surge is understood to be a socio-economic phenomenon where repair costs for the same damage are higher after large- versus small-scale natural disasters. It has reportedly increased monetary losses by 20 to 50%. In previous work, a model for the increased costs of reconstruction labor and materials was developed for hurricanes in the Southeast United States. The model showed that labor cost increases, rather than the material component, drove the total repair cost increases, and this finding could be extended to earthquakes. A study of past large-scale disasters suggested that there may be additional explanations for demand surge. Two such explanations specific to earthquakes are the exclusion of insurance coverage for earthquake damage and possible concurrent causation of damage from an earthquake followed by fire or tsunami. Additional research into these aspects might provide a better explanation for increased monetary losses after large- vs. small-scale earthquakes.

  14. Storm surge and river interaction in etuaries

    Science.gov (United States)

    Maskell, J.

    2012-04-01

    In coastal areas, particularly in regions developed on estuaries, extreme river flow can combine with storm surges to present a combined hazard. This combined risk is likely to be more prominent in estuaries where fluvial fresh water input comes from catchments in hilly regions where the dependence of extreme river discharge and sea level elevation can be most statistically significant (Svensson and Jones, 2004). The risk associated with these combined coastal hazards could increase due to climate change if there were an increase in the frequency of extreme weather events. The global (IPCC, 2007) and local (Woodworth et al., 2009) rise in mean sea-level will increase the magnitude of extreme sea levels and surges will act on a higher coastal sea level and therefore increase the risk to coastal property and infrastructure. This may be associated with an increase in precipitation during extreme storm events which will have a large impact on river flooding. Therefore, the need for accurate operational forecasting of storm events will increase with the focus shifting to changes in the extreme 'tail end' of the distribution of storm events. Ideally an operational model that integrates storm surge, wave and fluvial forecasting with inundation and simulates their combined influence would be most effective for planning with respect to flood plain development, evacuation and flood defence. Current operational storm surge models are typically based on two-dimensional depth-averaged shallow water equations (Flather, 2000). Inundation models often use an approximation of the original shallow water equations which neglect the inertial terms (Prestininzi et al., 2011). These 2D flood plain inundation models are often coupled with a 1D model of the main channel of a river or estuary which permits the exchange of mass but assumes a limited exchange of momentum (Bates et al., 2005). A finite volume model (FVCOM) is used to investigate the combined influence of storm surge and river

  15. Surge dynamics on Bering Glacier, Alaska, in 2008–2011

    Directory of Open Access Journals (Sweden)

    M. Braun

    2012-11-01

    Full Text Available A surge cycle of the Bering Glacier system, Alaska, is examined using observations of surface velocity obtained using synthetic aperture radar (SAR offset tracking, and elevation data obtained from the University of Alaska Fairbanks LiDAR altimetry program. After 13 yr of quiescence, the Bering Glacier system began to surge in May 2008 and had two stages of accelerated flow. During the first stage, flow accelerated progressively for at least 10 months and reached peak observed velocities of ~ 7 m d−1. The second stage likely began in 2010. By 2011 velocities exceeded 9 m d−1 or ~ 18 times quiescent velocities. Fast flow continued into July 2011. Surface morphology indicated slowing by fall 2011; however, it is not entirely clear if the surge is yet over. The quiescent phase was characterized by small-scale acceleration events that increased driving stresses up to 70%. When the surge initiated, synchronous acceleration occurred throughout much of the glacier length. Results suggest that downstream propagation of the surge is closely linked to the evolution of the driving stress during the surge, because driving stress appears to be tied to the amount of resistive stress provided by the bed. In contrast, upstream acceleration and upstream surge propagation is not dependent on driving stress evolution.

  16. A comparison of methods for determining the cotton field evapotranspiration and its components under mulched drip irrigation conditions: photosynthesis system, sap flow, and eddy covariance

    Science.gov (United States)

    Zhang, Z.; Tian, F.; Hu, H.

    2013-12-01

    A multi-scale, multi-technique study was conducted to measure evapotranspiration and its components in a cotton field under mulched drip irrigation conditions in northwestern China. Three measurement techniques at different scales were used: photosynthesis system (leaf scale), sap flow (plant scale), and eddy covariance (field scale). The experiment was conducted from July to September 2012. For upscaling the evapotranspiration from the leaf to the plant scale, an approach that incorporated the canopy structure and the relationships between sunlit and shaded leaves was proposed. For upscaling the evapotranspiration from the plant to the field scale, an approach based on the transpiration per unit leaf area was adopted and modified to incorporate the temporal variability in the relationships between the leaf area and the stem diameter. At the plant scale, the estimate of the transpiration based on the photosynthesis system with upscaling is slightly higher (18%) than that obtained by sap flow. At the field scale, the estimate of the transpiration obtained by upscaling the estimate based on sap flow measurements is also systematically higher (10%) compared to that obtained through eddy covariance during the cotton open boll growth stage when soil evaporation can be neglected. Nevertheless, the results derived from these three distinct methods show reasonable consistency at the field scale, which indicates that the upscaling approaches are reasonable and valid. Based on the measurements and the upscaling approaches, the evapotranspiration components were analyzed under mulched drip irrigation. During the cotton flower and bolling stages in July and August, the evapotranspiration are 3.94 and 4.53 mm day-1, respectively. The proportion of transpiration to evapotranspiration reaches 87.1% before drip irrigation and 82.3% after irrigation. The high water use efficiency is principally due to the mulched film above the drip pipe, the low soil water content in the inter

  17. Vision of irrigation

    Directory of Open Access Journals (Sweden)

    Fernando Braz-Tangerino

    2014-08-01

    Full Text Available Irrigation not only has been a key factor for the development and maintenance of human societies but it still plays this role now and it is foreseen that in the future as well. Its evolution has been constrained to the advance in knowledge on matters regarding Agronomy and Water Engineering and in technology however, many challenges deserve further research. It is worth to note that Brazil has strongly promoted irrigation in the last decade. Within the limited extension of this article, some current topics in irrigation, some of them are innovative such us the research line studying water flow in soil-plant in Mediterranean plants and its consequences on water use,. and future challenges are presented with the purpose of stimulate publication of Irrigation papers in the journal “Ingeniería del Agua” among Portuguese and Spanish language communities.

  18. Storm surge variational assimilation model

    Directory of Open Access Journals (Sweden)

    Shi-li HUANG

    2010-06-01

    Full Text Available To eliminate errors caused by uncertainty of parameters and further improve capability of storm surge forecasting, the variational data assimilation method is applied to the storm surge model based on unstructured grid with high spatial resolution. The method can effectively improve the forecasting accuracy of storm surge induced by typhoon through controlling wind drag force coefficient parameter. The model is first theoretically validated with synthetic data. Then, the real storm surge process induced by the TC 0515 typhoon is forecasted by the variational data assimilation model, and results show the feasibility of practical application.

  19. Waves of accelerated motion in a glacier approaching surge: the mini-surges of Variegated Glacier, Alaska, U.S.A.

    OpenAIRE

    Kamb, Barclay; Engelhardt, Hermann

    1987-01-01

    Periods of dramatically accelerated motion, in which the flow velocity increases suddenly from about 55 cm/d to a peak of 100-300 cm/d and then decreases gradually over the course of a day, occurred repeatedly during June and July 1978-81 in Variegated Glacier (Alaska), a surging-type glacier that surged in 1982-83. These "mini-surges" appear to be related mechanistically to the main surge. The flow-velocity peak propagates down-glacier as a wave at a speed of about 0.3 km/h, over a reach of ...

  20. Analytical solution for tension-saturated and unsaturated flow from wicking porous pipes in subsurface irrigation: The Kornev-Philip legacies revisited

    Science.gov (United States)

    Kacimov, A. R.; Obnosov, Yu. V.

    2017-03-01

    The Russian engineer Kornev in his 1935 book raised perspectives of subsurface "negative pressure" irrigation, which have been overlooked in modern soil science. Kornev's autoirrigation utilizes wicking of a vacuumed water from a porous pipe into a dry adjacent soil. We link Kornev's technology with a slightly modified Philip (1984)'s analytical solutions for unsaturated flow from a 2-D cylindrical pipe in an infinite domain. Two Darcian flows are considered and connected through continuity of pressure along the pipe-soil contact. The first fragment is a thin porous pipe wall in which water seeps at tension saturation; the hydraulic head is a harmonic function varying purely radially across the wall. The Thiem solution in this fragment gives the boundary condition for azimuthally varying suction pressure in the second fragment, ambient soil, making the exterior of the pipe. The constant head, rather than Philip's isobaricity boundary condition, along the external wall slightly modifies Philip's formulae for the Kirchhoff potential and pressure head in the soil fragment. Flow characteristics (magnitudes of the Darcian velocity, total flow rate, and flow net) are explicitly expressed through series of Macdonald's functions. For a given pipe's external diameter, wall thickness, position of the pipe above a free water datum in the supply tank, saturated conductivities of the wall and soil, and soil's sorptive number, a nonlinear equation with respect to the total discharge from the pipe is obtained and solved by a computer algebra routine. Efficiency of irrigation is evaluated by computation of the moisture content within selected zones surrounding the porous pipe.Plain Language SummarySubsurface irrigation by "automatic" gadgets like pitchers or porous pipes is a water saving technology which minimizes evaporative losses and deep percolation. Moisture is emitted by capillary suction of a relatively dry soil and "thirsty" roots just in "right quantities", spontaneously

  1. Present dynamics and future prognosis of a slowly surging glacier

    Directory of Open Access Journals (Sweden)

    G. E. Flowers

    2010-10-01

    Full Text Available Glacier surges are a well-known example of an internal dynamic oscillation whose occurrence is not a direct response to the external climate forcing, but whose character (e.g. period, mechanism may depend on the glacier's environmental or climate setting. We examine the dynamics of a small (~5 km2 valley glacier in the Yukon Territory of Canada, where two previous surges have been photographically documented and an unusually slow surge is currently underway. To characterize the dynamics of the present surge, and to speculate on the future of this glacier, we employ a higher-order flowband model of ice dynamics with a Coulomb-friction sliding law in both diagnostic and prognostic simulations. Diagnostic (force balance calculations capture the measured ice-surface velocity profile only when high basal water pressures (55–90% of flotation are prescribed over the central region of the glacier, consistent with where evidence of the surge has been identified. This leads to sliding accounting for 50–100% of the total surface motion. Prognostic simulations, where the glacier geometry evolves in response to a prescribed surface mass balance, reveal a significant role played by a large bedrock bump beneath the current equilibrium line of the glacier. This bump provides resistance to ice flow sufficient to cause the formation of a bulge in the ice-surface profile. We suggest that the bedrock bump contributes to the propensity for surges in this glacier, such that conditions suppressing ice-bulge formation over the bump may also inhibit surges. In our calculations such a situation arises for sufficiently negative values of mass balance. Collectively, these results corroborate our interpretation of the current glacier flow regime as indicative of a "slow surge", and confirm a relationship between surge incidence or character and the net mass balance. Our results also highlight the importance of glacier bed topography in controlling ice

  2. Irrigation Sprinklers Notice of Intent

    Science.gov (United States)

    High-efficiency irrigation sprinklers aim to deliver water more evenly to the landscape than traditional sprinklers and/or regulate outlet pressure to ensure a constant flow rate over a range of supply pressures.

  3. Present dynamics and future prognosis of a slowly surging glacier

    Directory of Open Access Journals (Sweden)

    G. E. Flowers

    2011-03-01

    Full Text Available Glacier surges are a well-known example of an internal dynamic oscillation whose occurrence is not a direct response to the external climate forcing, but whose character (i.e. period, amplitude, mechanism may depend on the glacier's environmental or climate setting. We examine the dynamics of a small (∼5 km2 valley glacier in Yukon, Canada, where two previous surges have been photographically documented and an unusually slow surge is currently underway. To characterize the dynamics of the present surge, and to speculate on the future of this glacier, we employ a higher-order flowband model of ice dynamics with a regularized Coulomb-friction sliding law in both diagnostic and prognostic simulations. Diagnostic (force balance calculations capture the measured ice-surface velocity profile only when non-zero basal water pressures are prescribed over the central region of the glacier, coincident with where evidence of the surge has been identified. This leads to sliding accounting for 50–100% of the total surface motion in this region. Prognostic simulations, where the glacier geometry evolves in response to a prescribed surface mass balance, reveal a significant role played by a bedrock ridge beneath the current equilibrium line of the glacier. Ice thickening occurs above the ridge in our simulations, until the net mass balance reaches sufficiently negative values. We suggest that the bedrock ridge may contribute to the propensity for surges in this glacier by promoting the development of the reservoir area during quiescence, and may permit surges to occur under more negative balance conditions than would otherwise be possible. Collectively, these results corroborate our interpretation of the current glacier flow regime as indicative of a slow surge that has been ongoing for some time, and support a relationship between surge incidence or character and the net mass balance. Our results also highlight the importance of glacier bed

  4. Impacts of changing cropping pattern on virtual water flows related to crops transfer: a case study for the Hetao irrigation district, China.

    Science.gov (United States)

    Liu, Jing; Wu, Pute; Wang, Yubao; Zhao, Xining; Sun, Shikun; Cao, Xinchun

    2014-11-01

    Analysis of cropping patterns is a prerequisite for their optimisation, and evaluation of virtual water flows could shed new light on water resources management. This study is intended to explore the effects of cropping pattern changes between 1960 and 2008 on virtual water flows related to crops transfer in the Hetao irrigation district, China. (1) The sown area of crops increased at an average rate of 3.57 × 10(3) ha year(-1) while the proportion of sown grain crops decreased from 92.83% in the 1960s to 50.22% in the 2000s. (2) Virtual water content decreased during the study period while net virtual water exports increased since the 1980s. (3) Assuming that the cropping pattern was constant and was equal to the average 1960s value, accumulated net virtual water export in 1980-2008 would have been 4.76 × 10(9) m(3) greater than that in the actual cropping pattern scenario. Cropping pattern changes in the Hetao irrigation district could not only be seen as resulting from the pursuit for higher economic returns, but also as a feedback response to limited water resources. A systematic framework is still needed for future cropping pattern planning by taking food security, continued agricultural expansion and other constraints into consideration. © 2014 Society of Chemical Industry.

  5. Lethal thermal impact at periphery of pyroclastic surges: evidences at Pompeii

    National Research Council Canada - National Science Library

    Mastrolorenzo, Giuseppe; Petrone, Pierpaolo; Pappalardo, Lucia; Guarino, Fabio M

    2010-01-01

    The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized...

  6. Lethal Thermal Impact at Periphery of Pyroclastic Surges: Evidences at Pompeii: e11127

    National Research Council Canada - National Science Library

    Giuseppe Mastrolorenzo; Pierpaolo Petrone; Lucia Pappalardo; Fabio M Guarino

    2010-01-01

      Background The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized...

  7. 7 CFR 58.218 - Surge tanks.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Surge tanks. 58.218 Section 58.218 Agriculture....218 Surge tanks. If surge tanks are used for hot milk, and temperatures of product including foam being held in the surge tank during processing, is not maintained at a minimum of 150 °F, then two...

  8. A surge of Perseibreen, Svalbard, examined using aerial photography and ASTER high resolution satellite imagery

    OpenAIRE

    Dowdeswell, Julian A.; Benham, Toby J.

    2003-01-01

    The identification of surge activity is important in assessing the duration of the active and quiescent phases of the surge cycle of Svalbard glaciers. Satellite and aerial photographic images are used to identify and describe the form and flow of Perseibreen, a valley glacier of 59 km2 on the east coast of Spitsbergen. Heavy surface crevassing and a steep ice front, indicative of surge activity, were first observed on Perseibreen in April 2002. Examination of high resolution (15 m) Advanced ...

  9. Surge dynamics on Bering Glacier, Alaska, in 2008–2011

    Directory of Open Access Journals (Sweden)

    M. Braun

    2012-03-01

    Full Text Available A 2008–2011 surge of Bering Glacier, Alaska is examined using observations of surface velocity and surface elevation change. Velocity measurements are obtained using synthetic aperture radar (SAR offset tracking and elevation data are obtained from the University of Alaska Fairbanks LiDAR altimetry program. Bering Glacier began to surge in May 2008 and had two phases of accelerated flow. The first phase accelerated progressively for at least 10 months and reached peak observed velocities of ~7 m d−1. Results suggest that during the quiescent phase, prior to the surge, periods of accelerated flow increased driving stresses up to 70% in a ~10 km-long section of the Lower Bering. When the first phase of the surge initiated, synchronous acceleration occurred throughout much of the glacier length, indicating widespread pressurization of the bed, but the largest accelerations initiated at the location where driving stress built up during quiescence. From there, rapid flow velocities propagated upstream and downstream across much of the glacier length and transpired as small, transient and unorganized propagation fronts. The second phase occurred in 2011 and was of comparable scale to the surge in 1993–1995, with velocities exceeding 9 m d−1 or ~18 times quiescent velocities.

  10. Modeling and control of surge and rotating stall in compressors

    Energy Technology Data Exchange (ETDEWEB)

    Gravdahl, Jan Tommy

    1998-12-31

    Compressors are used in power generation and a variety of other applications. This thesis contains new results in the field of modeling and control of rotating stall and surge in compressors. A close coupled valve is included in the Moore-Greitzer compression system model and controllers for both surge and rotating stall is derived using backstepping. Disturbances, constant and time varying, are then taken into account, and non-linear controllers are derived. Stability results are given. Then, passivity is used to derive a simple surge control law for the closed coupled valve. This propositional control law is shown to stabilize the system even in the presence of time varying disturbances in mass flow and pressure. A novel model for an axial compression system with non-constant compressor speed is derived by extending the Moore-Greitzer model. Rotating stall and surge is studied in connection with acceleration of the compressor. Finally, a model for a centrifugal compression system with time varying compressor speed is derived. The variable speed compressor characteristic is derived based on energy losses in the compressor components. Active control of surge in connection with varying speed is studied. Semi-global exponential stability of the compression system with both surge and speed control is proven. 103 refs., 38 figs., 5 tabs.

  11. Effects of irrigation efficiency on chemical transport processes

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Irrigation practices greatly affect sustainable agriculture development. In this study, we investigated the effects of irrigation efficiency on water flow and chemical transport in soils, which had significant impact on the environment. Field dye staining experiments were conducted at different soils with various irrigation amount. Image analysis was conducted to study the heterogeneous flow patterns and their relationships with the irrigation efficiency. Irrigation efficiency and its environmental effects were evaluated using various indictors, including application efficiency, deep percolation ratio, storage efficiency, and uniformity. Under the same irrigation condition, soil chemical distributions were more heterogeneous than soil water distributions. The distributions were mainly affected by soil texture, initial soil water content, and irrigation amount. Storage efficiency, irrigation uniformity, and deep percolation ratio increased with irrigation amount. Since the chemical distribution uniformity was lower than the water uniformity, the amount of chemical leaching increased sharply with decrease of irrigation uniformity, which resulted in high environmental risks of groundwater pollution.

  12. A High Density Storm Surge Monitoring Network: Evaluating the Ability of Wetland Vegetation to Reduce Storm Surge

    Science.gov (United States)

    Lawler, S.; Denton, M.; Ferreira, C.

    2013-12-01

    Recent tropical storm activity in the Chesapeake Bay and a potential increase in the predicted frequency and magnitude of weather systems have drawn increased attention to the need for improved tools for monitoring, modeling and predicting the magnitude of storm surge, coastal flooding and the respective damage to infrastructure and wetland ecosystems. Among other forms of flood protection, it is believed that coastal wetlands and vegetation can act as a natural barrier that slows hurricane flooding, helping to reduce the impact of storm surge. However, quantifying the relationship between the physical process of storm surge and its attenuation by wetland vegetation is an active area of research and the deployment of in-situ measuring devices is crucial to data collection efforts in this field. The United States Geological Survey (USGS) mobile storm-surge network has already successfully provided a framework for evaluating hurricane induced storm surge water levels on a regional scale through the use of in-situ devices installed in areas affected by storm surge during extreme events. Based on the success of the USGS efforts, in this study we adapted the monitoring network to cover relatively small areas of wetlands and coastal vegetation with an increased density of sensors. Groups of 6 to 10 water level sensors were installed in sites strategically selected in three locations on the Virginia coast of the lower Chesapeake Bay area to monitor different types of vegetation and the resulting hydrodynamic patterns (open coast and inland waters). Each group of sensors recorded time series data of water levels for both astronomical tide circulation and meteorological induced surge. Field campaigns were carried out to survey characteristics of vegetation contributing to flow resistance (i.e. height, diameter and stem density) and mapped using high precision GPS. A geodatabase containing data from field campaigns will support the development and calibration of

  13. The influence of climate during and after a glacial surge - A comparison of the last two surges of Fridtjovbreen, Svalbard

    Science.gov (United States)

    Lønne, Ida

    2014-02-01

    Glacial surges are periods of fast flow, often limited in space and time, and driven by internal conditions which are not fully explained. The quantity and variety of documented case-studies and settings demonstrate that the critical variables are difficult to isolate. In an alternative approach, two surges from the same basin were compared at Fridtjovhamna; one of the few known sites where this is possible. Fridtjovbreen is a polythermal glacier that has been through two recent surges: the last event (1991-2002) occurred during an unusually warm period in the high Arctic, whereas the previous surge culminated in 1861, around the Little Ice Age when many Svalbard-glaciers had their maximum Holocene extent. Based on a multi-disciplinary study, processes and landforms from the two episodes were compared with respect to ice-front movement rates, formation and decay of ice-cored moraines and glacial meltwater drainage patterns. The study demonstrates that moraines and meltwater traces from the oldest surge, locally well preserved, provide excellent opportunities for reconstructing the behavior of the ice-mass. The last surge, however, took place during a period with ablation rates never seen at this latitude, and 10 years after the maximum extent, the deglaciated areas onshore hardly show traces from the event.

  14. Methodology for surge pressure evaluation in a water injection system

    Energy Technology Data Exchange (ETDEWEB)

    Meliande, Patricia; Nascimento, Elson A. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Civil; Mascarenhas, Flavio C.B. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Lab. de Hidraulica Computacional; Dandoulakis, Joao P. [SHELL of Brazil, Rio de Janeiro, RJ (Brazil)

    2009-07-01

    Predicting transient effects, known as surge pressures, is of high importance for offshore industry. It involves detailed computer modeling that attempts to simulate the complex interaction between flow line and fluid in order to ensure efficient system integrity. Platform process operators normally raise concerns whether the water injection system is adequately designed or not to be protected against possible surge pressures during sudden valve closure. This report aims to evaluate the surge pressures in Bijupira and Salema water injection systems due to valve closure, through a computer model simulation. Comparisons among the results from empirical formulations are discussed and supplementary analysis for Salema system were performed in order to define the maximum volumetric flow rate for which the design pressure was able to withstand. Maximum surge pressure values of 287.76 bar and 318.58 bar, obtained in Salema and Bijupira respectively, using empirical formulations have surpassed the operating pressure design, while the computer model results have pointed the greatest surge pressure value of 282 bar in Salema system. (author)

  15. Brief Communication: Twelve-year cyclic surging episode at Donjek Glacier in Yukon, Canada

    Directory of Open Access Journals (Sweden)

    T. Abe

    2015-11-01

    Full Text Available Surge-type glaciers repeat their short active phase and much longer quiescent phase usually every several decades or longer, but detailed observations of the evolution cycles have been limited to a few glaciers. Here we report three surging episodes in 1989, 2001, and 2013 at Donjek Glacier in the Yukon, indicating remarkably regular and short repeat cycles of 12 years. The surging area is limited within the ~ 20 km section from the terminus, where the flow width significantly narrows than upstream, suggesting a strong control of the valley constriction on the surge dynamics.

  16. Brief Communication: Twelve-year cyclic surging episodes at Donjek Glacier in Yukon, Canada

    Science.gov (United States)

    Abe, Takahiro; Furuya, Masato; Sakakibara, Daiki

    2016-07-01

    Surge-type glaciers repeat their short active phase and their much longer quiescent phase usually every several decades or longer, but detailed observations of the evolution cycles have been limited to only a few glaciers. Here we report three surging episodes in 1989, 2001, and 2013 at Donjek Glacier in the Yukon, Canada, indicating remarkably regular and short repeat cycles of 12 years. The surging area is limited within the ˜ 20 km section from the terminus, originating in an area where the flow width significantly narrows downstream, suggesting a strong control of the valley constriction on the surge dynamics.

  17. Brief Communication: Twelve-year cyclic surging episode at Donjek Glacier in Yukon, Canada

    Science.gov (United States)

    Abe, T.; Furuya, M.; Sakakibara, D.

    2015-11-01

    Surge-type glaciers repeat their short active phase and much longer quiescent phase usually every several decades or longer, but detailed observations of the evolution cycles have been limited to a few glaciers. Here we report three surging episodes in 1989, 2001, and 2013 at Donjek Glacier in the Yukon, indicating remarkably regular and short repeat cycles of 12 years. The surging area is limited within the ~ 20 km section from the terminus, where the flow width significantly narrows than upstream, suggesting a strong control of the valley constriction on the surge dynamics.

  18. Irrigation System

    Science.gov (United States)

    1984-01-01

    Under contract with Marshall Space Flight Center, Midwest Research Institute compiled a Lubrication Handbook intended as a reference source for designers and manufacturers of aerospace hardware and crews responsible for maintenance of such equipment. Engineers of Lindsay Manufacturing Company learned of this handbook through NASA Tech Briefs and used it for supplemental information in redesigning gear boxes for their center pivot agricultural irrigation system.

  19. Medvezhiy Glacier surge in 2011

    Directory of Open Access Journals (Sweden)

    V. M. Kotlyakov

    2012-01-01

    Full Text Available The paper presents results of monitoring of the Medvezhiy Glacier state for the period from its surge of 2001 to the last pulsation of 2011. This monitoring is performed based on the photographing made from the Russian section of the International Space Station. Features, used for prediction of the glacier last movement, are pointed out. The earlier determined characteristic property of the Medvezhiy Glacier change from a phase of recovering to that of its fast movement has been substantiated. Mean period of the glacier pulsations, estimated from observations for the last century, is 13.5 years. A surge of the glacier left tributary is recognized.

  20. The 1982 eruptions of El Chichon volcano, Mexico (3): Physical properties of pyroclastic surges

    Science.gov (United States)

    Sigurdsson, H.; Carey, S. N.; Fisher, R. V.

    1987-04-01

    Two major pyroclastic surges generated during the 4 April 1982 eruption of El Chichon devastated an area of 153 km2 with a quasi-radial distribution around the volcano. The hot surge clouds carbonized wood throughout their extent and were too hot to allow accretionary lapilli formation by vapor condensation. Field evidence indicates voidage fraction of 0.99 in the surge cloud with extensive entrainment of air. Thermal calculations indicate that heat content of pyroclasts can heat entrained air and maintain high temperatures in the surge cloud. The dominant bed form of the surge deposits are sand waves shaped in dune forms with vertical form index of 10 20, characterized by stoss-side erosion and lee-side deposition of 1 10 cm reversely graded laminae. A systematic decrease in maximum lithic diameter with distance from source is accompanied by decrease in wavelength and amplitude. Modal analysis indicates fractionation of glass and pumice from the surge cloud relative to crystals, resulting in loss of at least 10% 25% of the cloud mass due to winnowing out of fines during surge emplacement. Greatest fractionation from the -1.0 0.0-∅ grain sizes reflects relatively lower pumice particle density in this range and segregation in the formative stages of the surge cloud. Extensive pumice rounding indicates abrasion during bed-load transport. Flow of pyroclastic debris in the turbulent surge cloud was by combination of bed-load and suspended-load transport. The surges are viewed as expanding pyroclastic gravity flows, which entrain and mix with air during transport. The balance between sedimentation at the base of the surge cloud and expansion due to entrainment of air contributed to low cloud density and internal turbulence, which persisted to the distal edge of the surge zone.

  1. Dune erosion during storm surges

    NARCIS (Netherlands)

    Van Thiel de Vries, J.S.M.

    2009-01-01

    Large parts of The Netherlands are protected from flooding by a narrow strip of sandy beaches and dunes. The aim of this thesis is to extend the existing knowledge of dune erosion during storm surges as it occurs along the Dutch coast. The thesis discusses: • A large scale dune erosion experiment to

  2. Improvement of Performance Range of Centrifugal Compressors Gas by Surge Line Modification Using Active Controller Based on Fuzzy Logic

    Directory of Open Access Journals (Sweden)

    Pezhman Mohammadi

    2012-04-01

    Full Text Available In this work, surge of prevention is a critical problem in oil and gas industries, particularly when return gas flow or gas flow reduces in transportation of gas pipelines. This paper is illustrated new results about surge control of centrifugal compressors .surge phenomenon is flow unsteady state in compressors which causes damages seriously in compressor construction. Furthermore, it also demonstrates in comparison with anti surge control ،active surge control expands stability range.Active surge control which based on fuzzy logic،is the main idea that used in this investigation. Using fuzzy controller causes an improvement in compressor's condition and increase performance range of the compressor, in addition to prevention of any instability in compressor. The simulation results is also satisfactory.

  3. Irrigated Agricultural Lands and Other Anthropogenic Land Disturbance in the Diamond Valley Flow System, Central Nevada, 2011

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data were created as part of a hydrologic study to characterize groundwater budgets and water quality in the Diamond Valley Flow System (DVFS), central Nevada....

  4. Geological Controls on Glacier Surging?: Statistics and Speculation

    Science.gov (United States)

    Flowers, G. E.; Crompton, J. W.

    2015-12-01

    Glacier surging represents an end-member behavior in the spectrum of ice dynamics, involving marked acceleration and high flow speeds due to abrupt changes in basal mechanics. Though much effort has been devoted to understanding the role of basal hydrology and thermal regime in fast glacier flow, fewer studies have addressed the potential role of the geologic substrate. One interesting observation is that surge-type glaciers appear almost universally associated with unconsolidated (till) beds, and several large-scale statistical studies have revealed correlations between glacier surging and bedrock properties. We revisit this relationship using field measurements. We selected 20 individual glaciers for sampling in a 40x40 km region of the St. Elias Mountains of Yukon, Canada. Eleven of these glaciers are known to surge and nine are not. The 20 study glaciers are underlain by lithologies that we have broadly classified into two types: metasedimentary only and mixed metasedimentary-granodiorite. We characterized geological and geotechnical properties of the bedrock in each basin, and analyzed the hydrochemistry and mineralogy and grain size distribution (GSD) of the suspended sediments in the proglacial streams. Here we focus on some intriguing results of the GSD analysis. Using statistical techniques, including significance testing and principal component analysis, we find that: (1) lithology determines GSD for non-surge-type glaciers, with metasedimentary basins associated with finer mean grain sizes and mixed-lithology basins with coarser mean grain sizes, but (2) the GSDs associated with surge-type glaciers are intermediate between the distributions described above, and are statistically indistinguishable between metasedimentary and mixed lithology basins. The latter suggests either that surge-type glaciers in our study area occur preferentially in basins where various processes conspire to produce a characteristic GSD, or that the surge cycle itself exerts an

  5. Comments on metal oxide surge arresters surges energy absorption capacity

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, M.L.B. [Escola Federal de Engenharia de Itajuba, Minas Gerais (Brazil); Zanetta, L.C. Jr. [E. Politecnica Univ. de Sao Paulo, Sao Paulo (Brazil)

    1996-12-31

    This paper presents an approach to determine the energy absorption capacity of metal oxide surge arrester resistors. The proposed approach deals with the discharge current peak versus discharge current time relation. A testing method and a statistical evaluation are proposed. After determining the discharge current withstanding limit of the tested metal oxide resistors, the prospective energy absorption capacity limit is computed. Finally, comments on the obtained results are presented.

  6. Swift snowmelt and floods (lahars) caused by great pyroclastic surge at Mount St Helens volcano, Washington, 18 May 1980

    Science.gov (United States)

    Waitt, R.B.

    1989-01-01

    The initial explosions at Mount St. Helens, Washington, on the moring of 18 May 1980 developed into a huge pyroclastic surge that generated catastrophic floods off the east and west flanks of the volcano. Near-source surge deposits on the east and west were lithic, sorted, lacking in accretionary lapilli and vesiculated ash, not plastered against upright obstacles, and hot enough to char wood - all attributes of dry pyroclastic surge. Material deposited at the surge base on steep slopes near the volcano transformed into high-concentration lithic pyroclastic flows whose deposits contain charred wood and other features indicating that these flows were hot and dry. Stratigraphy shows that even the tail of the surge had passed the east and west volcano flanks before the geomorphically distinct floods (lahars) arrived. This field evidence undermines hypotheses that the turbulent surge was itself wet and that its heavy components segregated out to transform directly into lahars. Nor is there evidence that meters-thick snow-slab avalanches intimately mixed with the surge to form the floods. The floods must have instead originated by swift snowmelt at the base of a hot and relatively dry turbulent surge. Impacting hot pyroclasts probably transferred downslope momentum to the snow surface and churned snow grains into the surge base. Melting snow and accumulating hot surge debris may have moved initially as thousands of small thin slushflows. As these flows removed the surface snow and pyroclasts, newly uncovered snow was partly melted by the turbulent surge base; this and accumulating hot surge debris in turn began flowing, a self-sustaining process feeding the initial flows. The flows thus grew swiftly over tens of seconds and united downslope into great slushy ejecta-laden sheetfloods. Gravity accelerated the floods to more than 100 km/h as they swept down and off the volcano flanks while the snow component melted to form great debris-rich floods (lahars) channeled into

  7. Winter speed-up of two surging glaciers in West Kunlun Shan, Northwestern Tibet

    Science.gov (United States)

    Yasuda, T.; Furuya, M.

    2015-12-01

    We detected winter speed-up of two surging glaciers in the West Kunlun Shan (WKS), based on satellite Synthetic Aperture Radar (SAR) images since 2007. Surging glacier is a surge-type glacier in the active phase, flowing rapidly and transporting ice masses into the down-glaciers. The WKS is located in northwestern Tibetan Plateau (TP) and is one of the driest and the coldest place around TP. Accumulation and ablation mostly occur in summer season from May to August [Zhang et al., 1989; Maussion et al., 2014]. Zhang et al. (1989) estimated the annual average precipitation and temperature near the equilibrium line altitude (5930 m) is 300 mm and -13.9 deg. C, respectively. Under this sub-polar environment, polythermal glaciers exist in the WKS [Aniya, 2008]. We detected development of two surging flow with unprecedented temporal resolution up to 11 days. The two surging initiated around 2000 and continued by 2015. Surging flow accelerated at least 200 m/year. Moreover, it seasonally fluctuated their flow speed up to 200% in early winter against those in spring to early summer. The observed seasonal modulation in the surface velocities strongly suggests the presence of surface meltwater and subsequent rerouting through englacial and subglacial drainage system under a years-long surging glacier in the sub-polar environment.

  8. INCREASED FLEXIBILITY OF TURBO-COMPRESSORS IN NATURAL GAS TRANSMISSION THROUGH DIRECT SURGE CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    Robert J. Mckee; Danny M. Deffenbaugh

    2003-12-01

    This annual progress report describes the second year's technical progress in a three-year program. This report summarizes what is known about internal flows as surge precursors in centrifugal compressors and focuses on accessing factors that affect pre-surge detection. An attempt is made in this analysis to identify and quantify factors concerning compressor design and operations that affect the detection of pre-surge conditions. This progress report presents results from recent laboratory tests conducted during the course of this second year. This project is co-funded by the Gas Machinery Research Council (GMRC) and by Siemens Energy and Automation (Siemens). The most recently available measured pre-surge internal flow data is parameterized to help identify factors that affect the indications that a compressor is approaching surge. Theoretical arguments are applied to access the factors that influence surge precursors and surge initiation in different centrifugal compressors. This work is considered a step in accessing the factors that affect the success or limitations of pre-surge detection in natural gas pipeline compressors.

  9. Medvezhiy Glacier surge in 2011

    OpenAIRE

    V. M. Kotlyakov; L. V. Desinov

    2012-01-01

    The paper presents results of monitoring of the Medvezhiy Glacier state for the period from its surge of 2001 to the last pulsation of 2011. This monitoring is performed based on the photographing made from the Russian section of the International Space Station. Features, used for prediction of the glacier last movement, are pointed out. The earlier determined characteristic property of the Medvezhiy Glacier change from a phase of recovering to that of its fast movement has been substantiated...

  10. Lake Borgne Surge Barrier Study

    Science.gov (United States)

    2010-09-01

    Savant , and Darla C. McVan September 2010 Approved for public release; distribution is unlimited. ERDC/CHL TR-10-10 September 2010 Lake...Borgne Surge Barrier Study S. Keith Martin, Gaurav Savant , and Darla C. McVan Coastal and Hydraulics Laboratory U.S. Army Engineer Research and...conducted by Keith Martin, Dr. Gaurav Savant , and Darla C. McVan. This work was conducted at the Coastal and Hydraulics Laboratory (CHL) of the

  11. Dynamic stall on a pitching and surging airfoil

    Science.gov (United States)

    Dunne, Reeve; McKeon, Beverley J.

    2015-08-01

    Vertical axis wind turbine blades undergo dynamic stall due to the large angle of attack variation they experience during a turbine rotation. The flow over a single blade was modeled using a sinusoidally pitching and surging airfoil in a non-rotating frame with a constant freestream flow at a mean chord Reynolds number of . Two-dimensional, time-resolved velocity fields were acquired using particle image velocimetry. Vorticity contours were used to visualize shear layer and vortex activity. A low-order model of dynamic stall was developed using dynamic mode decomposition, from which primary and secondary dynamic separation modes were identified. The interaction between these two modes was able to capture the physics of dynamic stall and as such can be extended to other turbine configurations and problems in unsteady aerodynamics. Results from the linear pitch/surge frame are extrapolated to the rotating VAWT frame to investigate the behavior of identified flow structures.

  12. The worst moment of superposed surge wave in upstream series double surge tanks of hydropower station

    Science.gov (United States)

    Teng, Y.; Yang, J. D.; Guo, W. C.; Chen, J. P.

    2016-11-01

    It is a consensus to consider the superposed working conditions when calculating the surge wave in surge tank of hydropower station with long diversion tunnel. For the hydropower station with single surge tank, the method of determining the worst superposed moment is mature. However, for the hydropower station with upstream series double surge tanks, research in this field is still blank. Based on an engineering project, this paper investigated the worst moments and the control superposed working conditions about the maximum surge level and the minimum surge level of upstream series double surge tanks using numerical simulation. In addition, the incidence relations between the worst moment of superposed surge wave and the different areal array and distance between the two surge tanks are also carried out. The results showed that: With the decrease of the distance between auxiliary surge tank and upstream reservoir, the maximum values of the highest surge levels in the two surge tanks always reach close to but a little earlier than the bigger one time when the inflowing discharges of the two surge tanks reach the maximum. It is similar to the minimum values of lowest surge levels in the two surge tanks which also reach close to but a little later than the bigger one time when the outflowing discharges of the two surges reach the maximum. Moreover, the closer the area of auxiliary surge tank to the area of main surge tank is, the closer the worst moment to the bigger one time when inflow or outflow of the two surges reach the maximum will become.

  13. Controls of evaporative irrigation return flows in comparison to seawater intrusion in coastal karstic aquifers in northern Sri Lanka: evidence from solutes and stable isotopes

    Science.gov (United States)

    Chandrajith, Rohana; Diyabalanage, Saranga; Premathilake, Mahinda; Hanke, Christian; van Geldern, Robert; Barth, Johannes A. C.

    2016-04-01

    region occurs through anthropogenic pollution, and particularly so due to agricultural activities. Extensive groundwater use in the peninsula may also further add concerns of active seawater intrusion after intense abstraction. The area should remain under close monitoring for both quality and quantity in order to protect groundwater as a vulnerable resource. Reference Chandrajith, R., Diyabalanage, S., Premathilake, K.M., Hanke, C., van Geldern, R. and Barth, J.A.C. (2016): Controls of evaporative irrigation return flows in comparison to seawater intrusion in coastal karstic aquifers in northern Sri Lanka: evidence from solutes and stable isotopes. - Science of the Total Environment, in press, [doi:10.1016/j.scitotenv.2016.01.050].

  14. Role of sediment in the design and management of irrigation canals : Sunsari Morang Irrigation Scheme, Nepal

    OpenAIRE

    Paudel, K.

    2010-01-01

    Sediment transport in irrigation canals The sediment transport aspect is a major factor in irrigation development as it determines to a large extent the sustainability of an irrigation scheme, particularly in case of unlined canals in alluvial soils. Investigations in this respect started since Kennedy published his channel-forming discharge theory in 1895. Subsequently different theories have been developed and are used around the world. All of them assume uniform and steady flow conditions ...

  15. Linkage of Rainfall-Runoff and Hurricane Storm Surge in Galveston Bay

    Science.gov (United States)

    Deitz, R.; Christian, J.; Wright, G.; Fang, N.; Bedient, P.

    2012-12-01

    In conjunction with the SSPEED Center, large rainfall events in the upper Gulf of Mexico are being studied in an effort to help design a surge gate to protect the Houston Ship Channel during hurricane events. The ship channel is the world's second largest petrochemical complex and the Coast Guard estimates that a one-month closure would have a $60 billion dollar impact on the national economy. In this effort, statistical design storms, such as the 24-hour PMP, as well as historical storms, like Hurricane Ike, Hurricane Katrina, and Hurricane Rita, are being simulated in a hydrologic/hydraulic model using radar and rain gauge data. VfloTM, a distributed hydrologic model, is being used to quantify the effect that storm size, intensity, and location has on timing and peak flows in the in the upper drainage area. These hydrographs were input to a hydraulic model with various storm surges from Galveston Bay. Results indicate that there is a double peak phenomenon with flows from the west draining days earlier than flows from the north. With storm surge typically lasting 36-48 hours, this indicates the flows from the west are interacting with the storm surge, whereas flows from the north would arrive once the storm surge is receding. Gate operations were optimized in the model to account for the relative timing of upland runoff and hurricane surge, and to quantify the capability of the gate structure to protect the Ship Channel industry.

  16. Identifying surging glaciers in the Central Karakoram for improved climate change impact assessment

    Science.gov (United States)

    Paul, Frank; Bolch, Tobias; Mölg, Nico; Rastner, Philipp

    2015-04-01

    Several recent studies have investigated glacier changes in the Karakoram mountain range, a region where glaciers behave differently (mass gain and advancing tongues) compared to most other regions in the world. Attribution of this behaviour to climate change is challenging, as many glaciers in the Karakoram are of surge type and have actively surged in the recent past. The measured changes in length, area, volume or velocity in this region are thus depending on the time-period analysed and include non-climatic components. Hence, a proper analysis of climate change impacts on glaciers in this region requires a separation of the surging from the non-surging glaciers. This is challenging as the former often lack the typical surface characteristics such as looped moraines (e.g. when they are steep and small) and/or they merge (during a surge) with a larger non-surging glacier and create looped moraines on its surface. By analysing time series of satellite images that are available since 1961, the heterogeneous behaviour of glaciers in the Karakoram can be revealed. In this study, we have analysed changes in glacier terminus positions in the Karakoram over different time periods from 1961 to 2014 for several hundred glaciers using Corona KH-4 and KH-4B, Hexagon KH-9, Terra ASTER, and Landsat MSS, TM, ETM+ and OLI satellite data. For the last 15 years, high-speed animations of image time-series reveal details of glacier flow and surge dynamics that are otherwise difficult to detect. For example, several of the larger glaciers with surging tributaries (e.g. Panmah, Sarpo Laggo, Skamri, K2 glacier) are stationary and downwasting despite the mass contributions from the surging glaciers. The analysis of the entire time series reveals a complex pattern of changes through time with retreating, advancing, surging and stationary glaciers that are partly regionally clustered. While most of the non-surging glaciers show only small changes in terminus position (±100 m or less

  17. Irrigation and Autocracy

    DEFF Research Database (Denmark)

    Bentzen, Jeanet Sinding; Kaarsen, Nicolai; Wingender, Asger Moll

    We show that societies with a history of irrigation-based agriculture have been less likely to adopt democracy than societies with a history of rainfed agriculture. Rather than actual irrigation, the empirical analysis is based on how much irrigation potentially can increase yields.Irrigation...

  18. Irrigation and Autocracy

    DEFF Research Database (Denmark)

    Bentzen, Jeanet Sinding; Kaarsen, Nicolai; Wingender, Asger Moll

    We show that societies with a history of irrigation-based agriculture have been less likely to adopt democracy than societies with a history of rainfed agriculture. Rather than actual irrigation, the empirical analysis is based on how much irrigation potentially can increase yields.Irrigation...

  19. Quantification of Sediment Transport During Glacier Surges and its Impact on Landform Architecture

    Science.gov (United States)

    Kjaer, K. H.; Schomacker, A.; Korsgaard, N. J.; Benediktsson, I. O.

    2008-12-01

    Multi-temporal DEMs (Digital Elevation Models) of glaciers and ice streams have successfully been used for extraction of changes in ice volume over time. In this study, we analysed DEMs of the Brúarjökull glacier forefield (Iceland) for 1945, prior to the last surge in 1964, and for 2003 in order to assess the effect of the surge on the sediment architecture in the forefield. The pre- and post-surge DEMs allow direct quantification of the sediment volumes that were re-distributed in the forefield by the surging ice mass in 1964. The surge-type glacier Brúarjökull has experienced six surges during the last four centuries; these are the largest surges known to have occurred in Iceland. During the most recent surge in 1963-64, the glacier advanced 8 km over a period of c. 3 months with a maximum ice flow velocity of 5 m/hr, and 700 km3 of ice were moved downglacier. The continued recession of Brúarjökull since the 1963-64 surge reveals a young landscape consisting of widely spaced and elongated bedrock hills interspaced with shallow sedimentary basins. The majority of the forefield is covered with a basal till sheet or glaciofluvial outwash fans. Mapping of the sediment thickness in the glacier forefield shows higher accumulation along ice marginal positions related to wedge formation during extremely rapid ice flow. Fast flow was sustained by overpressurized water causing sediment-bedrock decoupling beneath a thick sediment sequence that was coupled to the glacier. Elevation differences between the terrain surface in 1945 and 2003 confirm this scenario as huge quantities of sediment was eroded, deformed and transported during the last surge event. On the scale of individual landforms, it appears for a drumlin surface that is has been lowered 20 m from 1945-2003. Dead-ice melting can explain roughly 8 m of this lowering. Thus, the drumlin must have experienced 12 m of subglacial erosion during the 1964 surge. The imprint of at least four landform generations is

  20. Mapping Irrigation Potential in the Upper East Region of Ghana

    Science.gov (United States)

    Akomeah, E.; Odai, S. N.; Annor, F. O.; Adjei, K. A.; Barry, B.

    2009-04-01

    The Upper East Region together with the other two regions in Northern Ghana (Upper West and Northern Region) is seen as the locus of perennial food deficit (GPRS, 2003). Despite, the provision of over 200 small scale dams and various mechanisms aimed at poverty alleviation, the region is still plagued with poverty and yearly food shortages. To achieve food security and alleviate poverty in the region however, modernization of agriculture through irrigation is deemed inevitable. While it is true that considerable potential still exists for future expansion of irrigation, it cannot be refuted that water is becoming scarcer in the regions where the need for irrigation is most important, hence mapping the irrigation potential of the region will be the first step toward ensuring sound planning and sustainability of the irrigation developments. In this study, an attempt has been made to map out the irrigation potential of the Upper East Region. The river basin approach was used in assessing the irrigation potential. The catchments drained by The White Volta river, Red volta river, River Sissili and River Kulpawn were considered in the assessment. The irrigation potential for the sub basins was computed by combining information on gross irrigation water requirements for the selected cash crops, area of soil suitable for irrigation and available water resources. The capacity of 80%, 70%, 60% and 50% time of exceedance flow of the available surface water resources in the respective sub basins was estimated. The area that can be irrigated with this flow was computed with selected cropping pattern. Combining the results of the potential irrigable areas and the land use map of the respective sub basins, an irrigation potential map has been generated showing potential sites in the upper east region that can be brought under irrigation. Keywords: Irrigation potential, irrigation water requirement, land evaluation, dependable flow

  1. Observing storm surges from satellite altimetry

    Science.gov (United States)

    Han, Guoqi

    2016-07-01

    Storm surges can cause catastrophic damage to properties and loss of life in coastal communities. Thus it is important to enhance our capabilities of observing and forecasting storm surges for mitigating damage and loss. In this presentation we show examples of observing storm surges around the world using nadir satellite altimetry, during Hurricane Sandy, Igor, and Isaac, as well as other cyclone events. The satellite observations are evaluated against tide-gauge observations and discussed for dynamic mechanisms. We also show the potential of a new wide-swath altimetry mission, the Surface Water and Ocean Topography (SWOT), for observing storm surges.

  2. The effects of three techniques that change the wetting patterns over subsurface drip-irrigated potatoes

    Energy Technology Data Exchange (ETDEWEB)

    Elnesr, M.N.; Alazba, A.A.

    2015-07-01

    Wetting pattern enhancement is one of the goals of irrigation designers and researchers. In this study, we addressed three techniques (dual-lateral drip, intermittent flow and physical barrier methods) that change the wetting pattern of subsurface drip irrigation. To study their effect on the yield and water-use efficiency (WUE) of potatoes, field experiments were conducted for four seasons, during which the soil-water balance was continuously monitored using a set of capacitance probes. The results of the soil water patterns showed that both the dual-lateral and intermittent techniques increased lateral water movement and eliminated deep percolation, whereas the physical barrier had a limited effect on the top soil layer. The crop results indicated that the yield and WUE increased significantly in response to the application of the dual-lateral drip (up to 30%); the intermittent application also positively affected the yield (~10%) and the WUE (~14%), but these effects were not statistically significant according to the statistical model. The physical barrier showed a non-significant negative effect on the yield and WUE. These findings suggest the following recommended practices: the use of dual-lateral drip technique due to its beneficial results and its potential for increasing yields and reducing water consumption; the application of intermittent flow with more than three surges; and restricting the use of physical barriers to soils with high permeability. (Author)

  3. Reconnaissance level study Mississippi storm surge barrier

    NARCIS (Netherlands)

    Van Ledden, M.; Lansen, A.J.; De Ridder, H.A.J.; Edge, B.

    2012-01-01

    This paper reports a reconnaissance level study of a storm surge barrier in the Mississippi River. Historical hurricanes have shown storm surge of several meters along the Mississippi River levees up to and upstream of New Orleans. Future changes due to sea level rise and subsidence will further

  4. Influence of Surge on Extreme Roll Amplitudes

    DEFF Research Database (Denmark)

    Vidic-Perunovic, Jelena; Rognebakke, Olav; Pedersen, Preben Terndrup

    2008-01-01

    Interference of the wave-induced ship surge motion with roll dynamics has been studied. The surge motion has been included in a previously derived hydrodynamic roll prediction model in order to account for the ship speed variation due to the longitudinal incident wave pressure force. Depending on...

  5. Reconnaissance level study Mississippi storm surge barrier

    NARCIS (Netherlands)

    Van Ledden, M.; Lansen, A.J.; De Ridder, H.A.J.; Edge, B.

    2012-01-01

    This paper reports a reconnaissance level study of a storm surge barrier in the Mississippi River. Historical hurricanes have shown storm surge of several meters along the Mississippi River levees up to and upstream of New Orleans. Future changes due to sea level rise and subsidence will further inc

  6. Compression station anti-surge system considerations

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, Rainer; White, Robert C. [Solar Turbines Incorporated, Houston, TX (United States)

    2005-07-01

    Centrifugal compressor surge and its prevention have drawn significant attention in the literature. An important aspect of surge avoidance lies in the design of the compressor station and, in particular, the piping upstream and downstream of the compressor. Most anti-surge systems are perfectly capable of avoiding surge during normal operating conditions. However, unplanned emergency shutdowns present a significant challenge, and surge avoidance in these cases depends to a large degree on the station layout. Furthermore, the concepts used in the anti surge system (valves, piping, coolers) also impact the start-up of the station, or of individual units of the station. In this paper a simplified surge control system model is presented and used to develop simpler rules that help with proper sizing of upstream and downstream piping systems, as well as the necessary control element. Since the design of the surge control and recycle system also affects the start-up of units and stations, start-up considerations for stations with and without cooled recycle loops are discussed. (author)

  7. Luminescence dating of storm-surge sediment

    NARCIS (Netherlands)

    Cunningham, A.C.

    2011-01-01

    Geological evidence of storm surges has the potential to provide vital information on storm-surge risk. Sediment from the coastal dunes of the Netherlands contains evidence of extreme floods that occurred before reliable measurements of water level began. For these sediments to be useful in flood-ri

  8. Conductive surge testing of circuits and systems

    Science.gov (United States)

    Richman, P.

    1980-01-01

    Techniques are given for conductive surge testing of powered electronic equipment. The correct definitions of common and normal mode are presented. Testing requires not only spike-surge generators with a suitable range of open-circuit voltage and short-circuit current waveshapes, but also appropriate means, termed couplers, for connecting test surges to the equipment under test. Key among coupler design considerations is minimization of fail positives resulting from reduction in delivered surge energy due to the coupler. Back-filters and the lines on which they are necessary, are considered as well as ground-fault and ground potential rise. A method for monitoring delivered and resulting surge waves is mentioned.

  9. Development and Evaluation of Storm Surge Ensemble Forecasting for the Philippines Using JMA Storm Surge Model

    Science.gov (United States)

    Lapidez, J. P. B.; Tablazon, J. P.; Lagmay, A. M. F. A.; Suarez, J. K. B.; Santiago, J. T.

    2014-12-01

    The Philippines is one of the countries most vulnerable to storm surge. It is located in the North-western Pacific basin which is the most active basin in the planet. An average of 20 tropical cyclones enters the Philippine area of responsibility (PAR) every year. The archipelagic nature of the country with regions having gently sloping coasts and shallow bays also contribute to the formation of extreme surges. Last November 2013, storm surge brought by super typhoon Haiyan severely damaged several coastal regions in the Visayan Islands. Haiyan left more than 6 300 casualties and damages amounting to more than $ 2 billion. Extreme storm surge events such as this highlight the need to establish a storm surge early warning system for the country. This study explores the development and evaluation of storm surge ensemble forecasting for the Philippines using the Japan Meteorological Agency (JMA) storm surge model. 36-hour, 24-hour, and 12-hour tropical cyclone forecasts are used to generate an ensemble storm surge forecast to give the most probable storm surge height at a specific point brought by an incoming tropical cyclone. The result of the storm surge forecast is compared to tide gauge record to evaluate the accuracy. The total time of computation and dissemination of forecast result is also examined to assess the feasibility of using the JMA storm surge model for operational purposes.

  10. Surge dynamics in the Nathorstbreen glacier system, Svalbard

    Directory of Open Access Journals (Sweden)

    M. Sund

    2013-10-01

    Full Text Available Nathorstbreen glacier system (NGS recently experienced the largest surge in Svalbard since 1936, and is examined using spatial and temporal observations from DEM differencing, time-series of surface velocities from satellite synthetic aperture radar (SAR and other sources. The upper basins with maximum accumulation during quiescence correspond to regions of initial lowering. Initial speed-up exceeds quiescent velocities by a factor of several tens of times. This suggests that polythermal glaciers surges are initiated in the temperate area before mass is displaced downglacier. Subsequent downglacier mass displacement coincides with areas of 100–200 times increased velocities (stage 2. After > 5 yr the joint NGS terminus advanced abruptly into tidewater during winter. The advance was followed by upglacier propagation of crevasses, indicating a re-action following from the already displaced mass and extending flow. NGS advanced ca. 15 km, while another ca. 3 km length was lost due to calving. Surface lowering of ca. 50 m was observed in some upglacier areas and during 5 yr the total area increased by 20%. Maximum measured flow rates were at least 25 m d−1, 2500 times quiescence, while average velocities were about 10 m d−1. The surges of Zawadzkibreen cycle with ca. 70 yr periods.

  11. Cold Surge Activity Over the Gulf of Mexico in a Warmer Climate

    Directory of Open Access Journals (Sweden)

    Edgar Perez Perez

    2014-08-01

    Full Text Available Cold surges are a dominant feature of midlatitude tropical interaction. During the North Hemisphere (NH winter, midlatitude waves propagating from the Rocky Mountains into the Gulf of Mexico result in cold surges, also known as Nortes or Tehuantepecers, associated with severe weather over the southern part of Mexico. The magnitude of their intense surface winds, precipitation and drops in surface temperature depends on the characteristics of the midlatitude wave propagating into the tropics. The high spatial resolution (20km X 20km version of the TL959L60-AGC Model of the Meteorological Research Institute of Japan is used to examine changes in cold surge activity under the A1B greenhouse gas emission scenario for the 2080 - 2099 period. The model realistically reproduces the spatial and temporal characteristics of cold surges for the 1980 - 1989 control period. The effect of changes in baroclinicity, static stability and mean flow over North America suggest that in a warmer climate, increased cold surge activity over the Gulf of Mexico would occur. However, these systems would have shorter wavelength (higher phase speeds and shorter lifespans that could reduce the total amount of winter precipitation. The increased frequency of cold surges over the Gulf of Mexico would be a consequence of weaker baroclinicity and static stability in the lower troposphere over the cold surge genesis region, along with more dominant westerly winds, resulting from ENSO-like conditions in the atmospheric circulations over North America.

  12. Modelling of variable speed centrifugal compressors for anti-surge control

    OpenAIRE

    Aaslid, Per

    2009-01-01

    A mathematical model for simulation of gas compressor systems is developed. The model is designed for anti-surge control validation, and models a continuous flow gas compressor. The model also includes a cooler for gas cooling, a scrubber for liquid draining, and a recycle line with a control valve for anti-surge control. The system outlet has a check valve to prevent reversed flows. The model is one-dimensional and models pressure, temperature and mass flow for all system components, and als...

  13. Comparison of the Effectiveness of Four Different Types of Needles in Irrigating Endodontically Treated Teeth.

    Science.gov (United States)

    1980-02-08

    H. Ultrasonic disinfection of the root canal. Oral Surg 42(l):92-98, 1976. 12. Grossman, L.I. Endodontic Practice, Philadelphia, Lea and Febiger, 1976...different types of irrigating needles in the removal of contamination in vitro from the root canals of forty endodontically treated single-rooted...TYPES OF NEEDLES IN IRRIGATING ENDODONTICALLY TREATED TEETH E. Drobotij, DDS, MS Resident, Endodontics Dept. of Dentistry - PO Box 59 Madigan Army

  14. Ghana - Agriculture - Irrigation

    Data.gov (United States)

    Millennium Challenge Corporation — The Millennium Development Authority (MiDA) financed the construction of a new irrigation scheme in Kpong and the renovation of two irrigation schemes in Botanga and...

  15. 小白菜潮汐式栽培专用基质的筛选%Screening of Special Cultivation Substrate for Chinese Cabbage with Ebb-and-flow Irrigation

    Institute of Scientific and Technical Information of China (English)

    周晓平; 刘静波; 刘庆叶; 杨巍; 徐明喜; 王蓓; 甘小虎; 章鸥; 王东升

    2015-01-01

    对3种不同栽培基质和常规栽培基质(市场销售)在潮汐式灌溉模式下进行小白菜栽培试验,比较小白菜的植物学性状,筛选出适用于潮汐式灌溉的小白菜专用型栽培基质。研究结果表明,处理2(40%茶渣蚓粪、20%泥炭、20%蛭石、20%珍珠岩)培育的小白菜株高、生物量、株幅、SPAD 值均显著优于其他处理,栽培效果显著提高,可推荐作为潮汐式灌溉小白菜栽培的专用型基质。%In this paper,we used 3 different special cultivation substrates and 1 common cultivation substrate (for market sale)to take the experiment of Chinese cabbage planting with ebb-and-flow irrigation, and the botany characters of Chi-nese cabbage were observed to screening special Chinese cabbage cultivation substrates with Ebb-and-flow Irrigation. The result showed that the cultivation results of treatment 2 (40% tea leaf and vermicompost, 20% peat, 20% vermiculite, 20%perlite ) were significantly better than others in plant height, biomass, SPAD value, leaves spreading, it could be recom-mended as special cultivation substrates for Chinese cabbage with ebb-and-flow irrigation.

  16. The dynamics of surge in compression systems

    Indian Academy of Sciences (India)

    A N Vishwanatha Rao; O N Ramesh

    2007-02-01

    In air-compression systems, instabilities occur during operation close to their peak pressure-rise capability. However, the peak efficiency of a compression system lies close to this region of instability. A surge is a violent mode of instability where there is total breakdown of flow in the system and pressure-rise capability is lost drastically. Generally, all compression systems operate with a margin defined as the ‘surge margin’, and, consequently, system operational efficiency is lower. It is of interest to study compression-system surge to understand its dynamics in order to operate compression systems close to the instability for achieving high efficiency safely without encountering surge. Unsteady pressure data from a compression system, captured during surge oscillations, reveal many aspects of flow physics and are analysed to understand the surge dynamics of the system. A set of controlled experiments was conducted with a simple desktop experimental test set-up and essential aspects of surge dynamics have been characterised.

  17. WATER REQUIREMENT OF IRRIGATED GARLIC

    Science.gov (United States)

    A replicated field trial was conducted on the West side of the San Joaquin Valley to determine the crop coefficient and water requirements of irrigated garlic. Irrigation systems used included flood irrigation, subsurface drip irrigation, and surface drip irrigation. Irrigation levels were set at 5...

  18. Water Requirements Of Irrigated Garlic

    Science.gov (United States)

    A replicated field trial was conducted on the West side of the San Joaquin Valley to determine the crop coefficient and water requirements of irrigated garlic. Irrigation systems used included flood irrigation, subsurface drip irrigation, and surface drip irrigation. Irrigation levels were set at 5...

  19. Storm surge and tidal range energy

    Science.gov (United States)

    Lewis, Matthew; Angeloudis, Athanasios; Robins, Peter; Evans, Paul; Neill, Simon

    2017-04-01

    The need to reduce carbon-based energy sources whilst increasing renewable energy forms has led to concerns of intermittency within a national electricity supply strategy. The regular rise and fall of the tide makes prediction almost entirely deterministic compared to other stochastic renewable energy forms; therefore, tidal range energy is often stated as a predictable and firm renewable energy source. Storm surge is the term used for the non-astronomical forcing of tidal elevation, and is synonymous with coastal flooding because positive storm surges can elevate water-levels above the height of coastal flood defences. We hypothesis storm surges will affect the reliability of the tidal range energy resource; with negative surge events reducing the tidal range, and conversely, positive surge events increasing the available resource. Moreover, tide-surge interaction, which results in positive storm surges more likely to occur on a flooding tide, will reduce the annual tidal range energy resource estimate. Water-level data (2000-2012) at nine UK tide gauges, where the mean tidal amplitude is above 2.5m and thus suitable for tidal-range energy development (e.g. Bristol Channel), were used to predict tidal range power with a 0D modelling approach. Storm surge affected the annual resource estimate by between -5% to +3%, due to inter-annual variability. Instantaneous power output were significantly affected (Normalised Root Mean Squared Error: 3%-8%, Scatter Index: 15%-41%) with spatial variability and variability due to operational strategy. We therefore find a storm surge affects the theoretical reliability of tidal range power, such that a prediction system may be required for any future electricity generation scenario that includes large amounts of tidal-range energy; however, annual resource estimation from astronomical tides alone appears sufficient for resource estimation. Future work should investigate water-level uncertainties on the reliability and

  20. Impact of Low-Level Southerly Surges on Mixed Rossby Gravity Waves over the Central Pacific.

    Science.gov (United States)

    Fukutomi, Y.

    2014-12-01

    This study examines dynamical impacts of lower-tropospheric southerly wind surges originating in midlatitudes of the Southern Hemisphere (SH) on the development of mixed Rossby gravity (MRG) waves over the central Pacific during June-August 1979-2012, through the statistical analysis of the JRA-55 products and NOAA outgoing long wave radiation data. The central Pacific MRG waves are identified by an extended EOF (EEOF) analysis on 2-8-day filtered daily 850-hPa meridional wind anomalies during June-August 1979-2012. Composite analysis based on the leading EEOF time coefficients is able to capture the development of the MRG waves associated with a southerly surge originating in the SH extratropics. As a weak clockwise gyre as a part of an off-equatorial easterly wavetrain moves eastward and southeastward from the off-equatorial eastern Pacific into the equatorial central Pacific, the southerly surge penetrates into the equatorial tropics at around 150W. Then, the clockwise gyre develops into a MRG-type gyre over the central Pacific. A transition from an easterly wave-type gyre into a MRG-type gyre occurs associated with the southerly surge. The southerly surge forms a cross-equatorial flow on the western flank of the MRG-type gyre. The gyre is amplified when the southerly surge reaches the equatorial tropics. At the same time, convection coupled with the MRG-type gyre is enhanced. The southerly surges are originated in the midlatitude South Pacific, and they are induced by synoptic-scale baroclinic disturbances propagating along the SH midlatitude westerly jet. An eddy vorticity budget analysis indicates that the southerly surge plays an important role in spinning up the MRG-type gyre through transient advection of absolute vorticiy. A case study of a MRG-wave event in mid-July 2006 also illustrates development of a MRG wave associated with the southerly surge and an easterly wave-to-MRG wave transition.

  1. Thermal structure of Svalbard glaciers and implications for thermal switch models of glacier surging

    Science.gov (United States)

    Sevestre, Heïdi; Benn, Douglas I.; Hulton, Nicholas R. J.; Bælum, Karoline

    2015-10-01

    Switches between cold- and warm-based conditions have long been invoked to explain surges of High Arctic glaciers. Here we compile existing and new data on the thermal regime of six glaciers in Svalbard to test the applicability of thermal switch models. Two of the large glaciers of our sample are water terminating while one is land terminating. All three have a well-known surge history. They have a thick basal layer of temperate ice, superimposed by cold ice. A cold terminus forms during quiescence but is mechanically removed by calving on tidewater glaciers. The other three glaciers are relatively small and are either entirely cold or have a diminishing warm core. All three bear evidence of former warm-based thermal regimes and, in two cases, surge-like behavior during the Little Ice Age. In Svalbard, therefore, three types of glaciers have switched from slow to fast flow: (1) small glaciers that underwent thermal cycles during and following the Little Ice Age (switches between cold- and warm-based conditions), (2) large terrestrial glaciers which remain warm based throughout the entire surge cycle but develop cold termini during quiescence, and (3) large tidewater glaciers that remain warm based throughout the surge cycle. Our results demonstrate that thermal switching cannot explain the surges of large glaciers in Svalbard. We apply the concept of enthalpy cycling to the spectrum of surge and surge-like behavior displayed by these glaciers and demonstrate that all Svalbard surge-type glaciers can be understood within a single conceptual framework.

  2. Physical attributes of hurricane surges and their role in surge warning

    Science.gov (United States)

    Irish, J. L.

    2012-12-01

    In the last decade, the US has experienced some of its largest surges and hurricane-related damages on record. Effective evacuation in advance of a hurricane strike requires accurate estimation of the hurricane surge hazard that effectively conveys risk not only to government decision makers but also to the general public. Two primary challenges exist with the current structure for surge warning. First, existing computational methods for developing accurate, quantitative surge forecasts, namely surge height and inundation estimation, are limited by time and computational resources. Second, due primarily to the popularity and wide use of the Saffir-Simpson wind scale to convey the complete hurricane hazard, the public's perception of surge hazard is inaccurate. Here, we use dimensionless scaling and hydrodynamics arguments to quantify the influence of hurricane variables and regional geographic characteristics on the surge response. It will be shown that hurricane surge primarily scales with the hurricane's central pressure, and size and with continental shelf width at the landfall location (Irish et al. 2009, Nat. Haz.; Song et al. in press, Nat. Haz.). Secondary influences include the hurricane's forward speed and path. The developed physical scaling is applied in two ways: (1) as a means for expanding the utility of computational simulations for real-time surge height forecasting and (2) as a means to convey relative surge hazard via a readily evaluated algebraic surge scale. In the first application, the use of this physical scaling to develop surge response functions (SRF) enables instantaneous algebraic calculation of maximum surge height at any location of interest for any hurricane meteorological condition, without loss of accuracy gained via high-resolution computational simulation. When coupled with joint probability statistics, the use of SRFs enables rapid development of continuous probability density functions for probabilistic surge forecasting (Irish

  3. Fluid Lavage of Open Wounds (FLOW: design and rationale for a large, multicenter collaborative 2 × 3 factorial trial of irrigating pressures and solutions in patients with open fractures

    Directory of Open Access Journals (Sweden)

    2010-05-01

    Full Text Available Abstract Background Open fractures frequently result in serious complications for patients, including infections, wound healing problems, and failure of fracture healing, many of which necessitate subsequent operations. One of the most important steps in the initial management of open fractures is a thorough wound irrigation and debridement to remove any contaminants. There is, however, currently no consensus regarding the optimal approach to irrigating open fracture wounds during the initial operative procedure. The selection of both the type of irrigating fluid and the pressure of fluid delivery remain controversial. The primary objective of this study is to investigate the effects of irrigation solutions (soap vs. normal saline and pressure (low vs. high; gravity flow vs. high; low vs. gravity flow on re-operation within one year among patients with open fractures. Methods/Design The FLOW study is a multi-center, randomized controlled trial using a 2 × 3 factorial design. Surgeons at clinical sites in North America, Europe, Australia, and Asia will recruit 2 280 patients who will be centrally randomized into one of the 6 treatment arms (soap + low pressure; soap + gravity flow pressure; soap + high pressure; saline + low pressure; saline + gravity flow pressure; saline + high pressure. The primary outcome of the study is re-operation to promote wound or bone healing, or to treat an infection. This composite endpoint of re-operation includes a narrow spectrum of patient-important procedures: irrigation and debridement for infected wound, revision and closure for wound dehiscence, wound coverage procedures for infected or necrotic wound, bone grafts or implant exchange procedures for established nonunion in patients with postoperative fracture gaps less than 1 cm, intramedullary nail dynamizations in the operating room, and fasciotomies for compartment syndrome. Patients, outcome adjudicators, and data analysts will be blinded. We will compare

  4. Sediment and nutrient losses from an irrigated watershed.

    Science.gov (United States)

    Bjorneberg, D.; Ippolito, J.

    2011-12-01

    Irrigated agriculture is an essential part of stable food and fiber production. However, water returning from irrigated watersheds can contain excess sediment, nutrients and salts. Applying polyacrylamide to furrow irrigated fields reduces erosion 60 to 90%. Converting from furrow irrigation to sprinkler irrigation eliminates planned irrigation runoff necessary for uniform water application. Installing sediment ponds removes 50 to 80% of the suspended sediment from water before it flows back to major water bodies. In southern Idaho, irrigation watershed monitoring showed that implementing these conservation practices has reduced average suspended sediment loss from 460 kg/ha in 1970 to less than 100 kg/ha in 2005. These practices, however, have had less effect on soluble nutrients. Median nitrate concentrations have almost doubled from 1970 to 2005. Current research is focusing on identifying practices to reduce soluble nutrient losses.

  5. Experiment and surge analysis of centrifugal two-stage turbocharging system

    Institute of Scientific and Technical Information of China (English)

    Yituan HE; Chaochen MA

    2008-01-01

    To study a centrifugal two-stage turbocharging system's surge and influencing factors, a special test bench was set up and the system surge test was performed. The test results indicate that the measured parameters such as air mass flow and rotation speed of a high pressure (HP) stage compressor can be converted into corrected para-meters under a standard condition according to the Mach number similarity criterion, because the air flow in a HP stage compressor has entered the Reynolds number (Re) auto-modeling range. Accordingly, the reasons leading to a two-stage turbocharging system's surge can be analyzed according to the corrected mass flow characteristic maps and actual operating conditions of HP and low pressure (LP) stage compressors.

  6. New insights in the ongoing surge of the Austfonna icecap

    Science.gov (United States)

    Schellenberger, T.; Dunse, T.; Kääb, A.; Hagen, J. O.; Schuler, T.; Reijmer, C.

    2014-12-01

    Basin-3, a major drainage basin of the Austfonna icecap in NE-Svalbard switched to full surge mode in autumn 2012 after a multiannual, stepwise acceleration of its northern branch. A time series of velocity maps from repeat TerraSAR-X acquisitions revealed a maximum speed at the terminus of >18 m d-1 around the turn of the year 2012. The frontal ablation of Basin-3 was estimated to 4.2±1.6 Gt a-1 between April 2012 and May 2013, tripling the total dynamic mass loss from the largest icecap in the Eurasian arctic. Today, TerraSAR-X, Radarsat-2 and GPS data show that the surge is still ongoing. While the speed at the calving front dropped to 10 m d-1 until July 2014, areas further inland continued to accelerate after the climax, and 10 m d-1 were also measured ~20 km inland in summer 2014. This development will be further investigated by exploiting a time series of velocity maps based on Radarsat-2 Fine Beam data starting from July 2014, which will, other than the TerraSAR-X data, cover almost the entire fast flowing part of the basin. By combining both datasets we will extend the estimation of the frontal ablation and related sea-level rise contribution of the Basin-3 surge.

  7. Glacier surge mechanism: 1982-1983 surge of variegated glacier, alaska.

    Science.gov (United States)

    Kamb, B; Raymond, C F; Harrison, W D; Engelhardt, H; Echelmeyer, K A; Humphrey, N; Brugman, M M; Pfeffer, T

    1985-02-01

    The hundredfold speedup in glacier motion in a surge of the kind the kind that took place in Variegated Glacier in 1982-1983 is caused by the buildup of high water pressure in the basal passageway system, which is made possible by a fundamental and pervasive change in the geometry and water-transport characteristics of this system. The behavior of the glacier in surge has many remarkable features, which can provide clues to a detailed theory of the surging process. The surge mechanism is akin to a proposed mechanism of overthrust faulting.

  8. 考虑回归水重复利用的灌区用水评价指标%Water use assessment indices under the influence of return flows in irrigation districts

    Institute of Scientific and Technical Information of China (English)

    刘路广; 崔远来; 吴瑕

    2013-01-01

    为了正确评价灌区用水效率及用水效益,构建了考虑回归水重复利用的灌区用水效率及效益指标.利用地表水-地下水耦合模型、SWAP模型和线性模型对柳园口灌区的水量和作物产量进行了分布式模拟,在此基础上,对柳园口灌区不同用水模式以及田间不同节水灌溉模式下的灌区用水效率及效益指标进行了计算,分析不同节水措施对灌区用水效率及效益指标的影响规律.结果表明,井渠结合调控模式和田间节水灌溉模式对柳园口灌区不同区域用水效率及效益的影响效果不同,但均能提高灌区总体的用水效率及效益.%In order to accurately evaluate the water use efficiency in irrigation districts,several new indices were proposed to measure the efficiency and benefit of water use in this study.The water balance components are simulated using integrated surface and groundwater models in the Liuyuankou Irrigation District (LID).Thus,the new indices take into account the influence of return flows.The Statewide Agricultural Production (SWAP) model and a liner model are used to simulate the crop yields in the LID.On this basis,the indices measuring water use efficiency and benefit can be calculated and analyzed for different patterns of water-use.The influence of various water saving measures on the efficiency and benefit of water use is discussed.Results show that although,over different regions of LID,the results of well-canal combined irrigation mode and water-saving irrigation mode can be different in terms of water use efficiency.The use of both modes can improve the overall efficiency and benefit of water use in the LID.The study provides a theoretical method and theoretical basis for the water use assessment in irrigation districts.

  9. Artificial Neural Network forecasting of storm surge water levels at major estuarine ports to supplement national tide-surge models and improve port resilience planning

    Science.gov (United States)

    French, Jon; Mawdsley, Robert; Fujiyama, Taku; Achuthan, Kamal

    2017-04-01

    Effective prediction of tidal storm surge is of considerable importance for operators of major ports, since much of their infrastructure is necessarily located close to sea level. Storm surge inundation can damage critical elements of this infrastructure and significantly disrupt port operations and downstream supply chains. The risk of surge inundation is typically approached using extreme value analysis, while short-term forecasting generally relies on coastal shelf-scale tide and surge models. However, extreme value analysis does not provide information on the duration of a surge event and can be sensitive to the assumptions made and the historic data available. Also, whilst regional tide and surge models perform well along open coasts, their fairly coarse spatial resolution means that they do not always provide accurate predictions for estuarine ports. As part of a NERC Environmental Risks to Infrastructure Innovation Programme project, we have developed a tool that is specifically designed to forecast the North Sea storm surges on major ports along the east coast of the UK. Of particular interest is the Port of Immingham, Humber estuary, which handles the largest volume of bulk cargo in the UK including major flows of coal and biomass for power generation. A tidal surge in December 2013, with an estimated return period of 760 years, partly flooded the port, damaged infrastructure and disrupted operations for several weeks. This and other recent surge events highlight the need for additional tools to supplement the national UK Storm Tide Warning Service. Port operators are also keen to have access to less computationally expensive forecasting tools for scenario planning and to improve their resilience to actual events. In this paper, we demonstrate the potential of machine learning methods based on Artificial Neural Networks (ANNs) to generate accurate short-term forecasts of extreme water levels at estuarine North Sea ports such as Immingham. An ANN is

  10. Comparison of the Effects of Various Irrigating Solutions on Dentine Permeability.

    Science.gov (United States)

    1980-09-01

    Irrigant. Oral Surg 41(20):175-177, 1980. 17. Seltzer , Samuel, and Bender , I.B. The Dental Pulp, ed. 2. Philadelphia, Lippincott, 1975, p 242. 18...microscopic study. Acta Odont Scand 30:291-311, 1972. 3. Baker, N.A.; Eleazer, P.D.; Averbach, R.E.; and Seltzer , S. Scanning electron microscopic study of

  11. Effects of irrigation efficiency on chemical transport processes

    Institute of Scientific and Technical Information of China (English)

    WANG Kang; ZHANG RenDuo; SHENG Feng

    2009-01-01

    Irrigation practices greatly affect sustainable agriculture development.In this study, we investigated the effects of irrigation efficiency on water flow and chemical transport in soils, which had significant impact on the environment.Field dye staining experiments were conducted at different soils with various irrigation amount.Image analysis was conducted to study the heterogeneous flow patterns and their relationships with the irrigation efficiency.Irrigation efficiency and its environmental effects were evaluated using various indictors, including application efficiency, deep percolation ratio, storage effi-ciency, and uniformity.Under the same irrigation condition, soil chemical distributions were more het-erogeneous than soil water distributions.The distributions were mainly affected by soil texture, initial soil water content, and irrigation amount.Storage efficiency, irrigation uniformity, and deep percolation ratio increased with irrigation amount.Since the chemical distribution uniformity was lower than the water uniformity, the amount of chemical leaching increased sharply with decrease of irrigation uni-formity, which resulted in high environmental risks of groundwater pollution.

  12. Comparison of Irrigation Times Using Gravity and High-Pressure Lavage.

    Science.gov (United States)

    Muscatelli, Stefano; Howe, Andrea; O'Hara, Nathan N; O'Toole, Robert V; Sprague, Sheila A; Slobogean, Gerard P

    2017-01-11

    The benefits of high-pressure pulsatile lavage for open fracture irrigation have been controversial based on conflicting experimental animal research. Recently published data definitively demonstrated that irrigation pressure does not affect the incidence of reoperation for the treatment of open fractures. However, proponents of pulsatile lavage argue a faster irrigation time is an important benefit of the high-pressure treatment. The purpose of this study was to determine the difference in irrigation time between gravity and high-pressure lavage. The experimental setup was designed to mimic clinical practice and compared mean irrigation flow times for high-pressure pulsatile lavage and gravity flow with 2 commonly used tube diameters. Each irrigation setup was tested 5 times at 3 different irrigation bag heights. Analysis of variance and Student's t tests were used to compare the mean flow times of 3 irrigation methods at each height and among the 3 heights for each irrigation method. The mean irrigation flow time in the various experimental models ranged from 161 to 243 seconds. Gravity irrigation with wide tubing was significantly faster than pulsatile lavage or gravity with narrow tubing (P<.001). Increasing irrigation bag height had only a marginal effect on the overall flow times (<9% difference). The difference in mean flow time among the testing techniques was slightly longer than 1 minute, which is unlikely to have a material impact on procedural costs, operating times, and subsequent gains in patient safety. [Orthopedics. 201x; xx(x):xx-xx.].

  13. The comparison between two irrigation regimens on the dentine wettability for an epoxy resin based sealer by measuring its contact angle formed to the irrigated dentine

    Directory of Open Access Journals (Sweden)

    Rayapudi Phani Mohan

    2015-01-01

    Conclusion: An irrigation regimen consisting of NaOCl with either EDTA or EDTAC solution as a final irrigant influences the dentine wettability and contact angle of a sealer. EDTAC as a final irrigant facilitates better dentin wettability than EDTA for AH Plus to promote its better flow and adhesion.

  14. An Investigation of Surge in a High-Speed Centrifugal Compressor Using Digital PIV

    Science.gov (United States)

    Wernet, Mark P.; Bright, Michelle M.; Skoch, Gary J.

    2002-01-01

    Compressor stall is a catastrophic breakdown of the flow in a compressor, which can lead to a loss of engine power, large pressure transients in the inlet/nacelle and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge can significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify the dynamic changes occurring in the flow field prior to rotating stall and surge in order to successfully control these events. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to simultaneously capture transient velocity and pressure measurements in the non-stationary flow field during compressor surge. DPIV is an instantaneous, planar measurement technique which is ideally suited for studying transient flow phenomena in high speed turbomachinery and has been used previously to successfully map the stable operating point flow field in the diffuser of a high speed centrifugal compressor. Through the acquisition of both DPIV images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.

  15. Surge-tectonic evolution of southeastern Asia: a geohydrodynamics approach

    Science.gov (United States)

    Meyerhoff, Arthur A.

    the surge channels—form an anastomosing E-W pattern southern Asiatic Russia, Mongolia, western China, the Qinghai-Tibetan region, and northern India and Pakistan. Such an anastomosing pattern indicates that flow is an active process in the surge channels. Surface studies of phenomena that might be associated with the surge channels soon revealed that all active channels are characterized by higher-than-normal heat flow (> 55 mW m -2, thermal springs and elevated ground-water temperatures, volvanic phenomena, bands of microearthquakes, and linear belts of faults, fractures, and fissures. The latter are especially visible on satellite images. The bands of high heat flow, thermal springs, microearthquakes, and faults-fractures-fissures almost exactly coincide. The fault-fracture-fissure systems are interpreted to be streamlines caused by flow in the surge channels—a consequence of Stokes's Law (an expression of Newton's Second Law of Motion)-and show that Poiseuille flow must dominate in the channels. Hence, the mechanism producing the belts of linear faults-fractures-fissures is viscous drag, produced by fluid motions. The eastward flow of the magma in the channels is demonstrated clearly in the tectonic patterns of southeastern Asia. In the northern part of the region studied, the E-W striking anastomosing surge channels (tectonic belts) splay northeastward into the coastal regions of Russia. In the south, they splay southward and southeastward through the Malay Peninsula and Indonesia. The open horsetail structures thus created prove that flow is W-E. The presence of the two splay directions, NE and S-SE, indicates in addition that a barrier to eastward flow must lie directly east of Asia. In this author's opinion, this barrier is the existing Benioff zone, because the same NE and S-SE splay patterns are present on each of the paleotectonic maps that have been prepared for nine time intervals from the beginning of Sinian (latest Proterozoic) time to the present. The

  16. Model simulation of storm surge potential for Andaman islands

    Digital Repository Service at National Institute of Oceanography (India)

    Kumar, V.S.; RameshBabu, V.; Babu, M.T.; Dhinakaran, G.; Rajamanickam, G.V.

    ) for storm surge forecasting at the eastern coast of India. Flather (1994) has applied another analytical model of Holland (1980) for wind and pressure fields in the case of surge simulation, forced by April 1991 Bangladesh storm. The basic atmospheric... parameters remain the same in all the parameterization schemes of storm wind field. Storm Surge Model Storm surge operational models are in use for a long time for forecasting and warning of storm surge disasters bordering the coasts in the parts of northern...

  17. Root canal irrigants.

    Science.gov (United States)

    Kandaswamy, Deivanayagam; Venkateshbabu, Nagendrababu

    2010-10-01

    Successful root canal therapy relies on the combination of proper instrumentation, irrigation, and obturation of the root canal. Of these three essential steps of root canal therapy, irrigation of the root canal is the most important determinant in the healing of the periapical tissues. The primary endodontic treatment goal must thus be to optimize root canal disinfection and to prevent reinfection. In this review of the literature, various irrigants and the interactions between irrigants are discussed. We performed a Medline search for English-language papers published untill July 2010. The keywords used were 'root canal irrigants' and 'endodontic irrigants.' The reference lists of each article were manually checked for additional articles of relevance.

  18. Armenia - Irrigation Infrastructure

    Data.gov (United States)

    Millennium Challenge Corporation — This study evaluates irrigation infrastructure rehabilitation in Armenia. The study separately examines the impacts of tertiary canals and other large infrastructure...

  19. Investigating changes in basal conditions of Variegated Glacier prior and during its 1982–1983 surge

    Directory of Open Access Journals (Sweden)

    O. Gagliardini

    2011-05-01

    Full Text Available The Variegated Glacier (Alaska is known to surge periodically after a sufficient amount of cumulative mass balance is reached, but this observation is difficult to link with changes in the basal conditions. Here, using a 10-year dataset, consisting in surface topography and surface velocity observations along a flow line for 25 dates, we have reconstructed the evolution of the basal conditions prior and during the 1982–1983 surge. The model solves the full-Stokes problem along the central flow line using the finite element method. For the 25 dates of the dataset, the basal friction parameter distribution is inferred using the inverse method proposed by Arthern and Gudmundson (2010. This method is here slightly modified by incorporating a regularisation term in the cost function to avoid short wave length changes in the friction parameter. Our results indicate that dramatic changes in the basal conditions occurred between 1973 to 1983. Prior to the surge, periodical changes can be observed between winter and summer, with a regular increase of the sliding from 1973 to 1982. During the surge, the basal friction decreased dramatically and an area of very low friction moved from the upper part of the glacier to its terminus. Using a more complex friction law, these changes in basal sliding are then interpreted in terms of basal water pressure. It confirms that dramatic changes took place in the subglacial drainage system of Variegated Glacier, moving from a relatively efficient drainage system prior to the surge to an inefficient one during the surge. By reconstructing the water pressure evolution at the base of the glacier it is possible to infer realistic scenarios for the hydrological history leading to the occurrence of a surge.

  20. The SRFR 5 modeling system for surface irrigation

    Science.gov (United States)

    The SRFR program is a modeling system for surface irrigation. It is a central component of WinSRFR, a software package for the hydraulic analysis of surface irrigation systems. SRFR solves simplified versions of the equations of unsteady open channel flow coupled to a user selected infiltration mod...

  1. Sedimentological features of the surge emitted during the August, 2006 pyroclastic eruption at Tungurahua volcano (Ecuador)

    Science.gov (United States)

    Douillet, G.; Goldstein, F.; Lavallee, Y.; Hanson, J. B.; Kueppers, U.; Robin, C.; Ramon, P.

    2009-12-01

    Tungurahua volcano, Ecuador, is a stratovolcano, which began a new eruptive phase in 1999. Notable pyroclastic Density Currents (PDC) were generated in July (VEI 2) and August (VEI 3) 2006 and covered its N and W flanks. PDCs and associated lahars represent a major hazard for 20,000 inhabitants and an hydrological dam. The volcano has been monitored by the Instituto Geofisico of the Escuela Politécnica Nacional of Quito, since 1988. Field work carried out in 2009 provide information on the behavior of the fine-grained fraction of the PDC (i.e., surge) during transport and deposition. We mapped out the sedimentological characteristics of the deposits and distinguished three depositional environments: 1- The core of the deposit, up to several m in thickness, is confined to valleys and consists of poorly-sorted lapilli scoria and blocks (cm to m scale) and a small fraction of ash matrix. Ongoing analysis of the ash matrix will help to understand the link between the main PDC and the associated surge. 2- On ridges and outer margins of valleys, the deposits total a thickness of 10s to 100s cm and consist of fine- to coarse-grain ashes organized in cm-scale beds. Horizontal to cross bed laminations with 10-cm long wavelength prevail. They are typical of deposition under sustained high-energy current, which we associate with the flow of a surge. 3- In the distal part of surge deposits, we observe fine grained surge deposits with a thickness up to ca. 5 m. The characteristic structures are curved crested dunes, 10s of cm high and up to 10s of m long, with dip angles ranging from 15 to 35° and a strongly asymmetric shape. The steepest side tends to be the upslope face. Dunes show mainly a climbing structure, with beds cm in thickness, but some are more complicated, containing cut and fill structures, interpreted as late-stage pulses of energetic turbulence. No displacement dunes were observed in this area. Using the flow direction given by 100s of dunes, we provide

  2. The optimization of design parameters for surge relief valve for pipeline systems

    Science.gov (United States)

    Kim, Hyunjun; Hur, Jisung; Kim, Sanghyun

    2017-06-01

    Surge is an abnormal pressure which induced by rapid changes of flow rate in pipeline systems. In order to protect pipeline system from the surge pressure, various hydraulic devices have been developed. Surge-relief valve(SRV) is one of the widely applied devices to control surge due to its feasibility in application, efficiency and cost-effectiveness. SRV is designed to automatically open under abnormal pressure and discharge the flow and makes pressure of the system drop to the allowable level. The performance of the SRV is influenced by hydraulics. According to previous studies, there are several affecting factors which determine performance of the PRV such as design parameters (e.g. size of the valve), system parameters (e.g. number of the valves and location of the valve), and operation parameters (e.g. set point and operation time). Therefore, the systematic consideration for factors affecting performance of SRV is required for the proper installation of SRV in the system. In this study, methodology for finding optimum parameters of the SRV is explored through the integration of Genetic Algorithm(GA) into surge analysis.

  3. Changes in the Earth's largest surge glacier system from satellite and airborne altimetry and imagery

    Science.gov (United States)

    Trantow, T.; Herzfeld, U. C.

    2015-12-01

    The Bering-Bagley Glacier System (BBGS), Alaska, one of the largest ice systems outside of Greenland and Antarctica, has recently surged (2011-2013), providing a rare opportunity to study the surge phenomenon in a large and complex system. Understanding fast-flowing glaciers and accelerations in ice flow, of which surging is one type, is critical to understanding changes in the cryosphere and ultimately changes in sea level. It is important to distinguish between types of accelerations and their consequences, especially between reversible or quasi-cyclic and irreversible forms of glacial acceleration, but current icesheet models treat all accelerating ice identically. Additionally, the surge provides an exceptional opportunity to study the influence of surface roughness and water content on return signals of altimeter systems. In this presentation, we analyze radar and laser altimeter data from CryoSat-2, NASA's Operation IceBridge (OIB), the ICESat Geoscience Laser Altimeter System (GLAS), ICESat-2's predecessor the Multiple Altimeter Beam Experimental Lidar (MABEL), and airborne laser altimeter and imagery campaigns by our research group. These measurements are used to study elevation, elevation change and crevassing throughout the glacier system. Analysis of the imagery from our airborne campaigns provides comprehensive characterizations of the BBGS surface over the course of the surge. Results from the data analysis are compared to numerical modeling experiments.

  4. Irrigation of human prepared root canal – ex vivo based computational fluid dynamics analysis

    Science.gov (United States)

    Šnjarić, Damir; Čarija, Zoran; Braut, Alen; Halaji, Adelaida; Kovačević, Maja; Kuiš, Davor

    2012-01-01

    Aim To analyze the influence of the needle type, insertion depth, and irrigant flow rate on irrigant flow pattern, flow velocity, and apical pressure by ex-vivo based endodontic irrigation computational fluid dynamics (CFD) analysis. Methods Human upper canine root canal was prepared using rotary files. Contrast fluid was introduced in the root canal and scanned by computed tomography (CT) providing a three-dimensional object that was exported to the computer-assisted design (CAD) software. Two probe points were established in the apical portion of the root canal model for flow velocity and pressure measurement. Three different CAD models of 27G irrigation needles (closed-end side-vented, notched open-end, and bevel open-end) were created and placed at 25, 50, 75, and 95% of the working length (WL). Flow rates of 0.05, 0.1, 0.2, 0.3, and 0.4 mL/s were simulated. A total of 60 irrigation simulations were performed by CFD fluid flow solver. Results Closed-end side-vented needle required insertion depth closer to WL, regarding efficient irrigant replacement, compared to open-end irrigation needle types, which besides increased velocity produced increased irrigant apical pressure. For all irrigation needle types and needle insertion depths, the increase of flow rate was followed by an increased irrigant apical pressure. Conclusions The human root canal shape obtained by CT is applicable in the CFD analysis of endodontic irrigation. All the analyzed values –irrigant flow pattern, velocity, and pressure – were influenced by irrigation needle type, as well as needle insertion depth and irrigant flow rate. PMID:23100209

  5. Comparison of a continuous ultrasonic irrigation device and conventional needle irrigation in the removal of root canal debris.

    Science.gov (United States)

    Curtis, Tyson O; Sedgley, Christine M

    2012-09-01

    The purpose of this in vitro study was to compare a continuous ultrasonic irrigation device (VPro StreamClean System [VSS], Vista Dental Products, Racine, WI) with conventional needle irrigation when used as a final irrigation procedure to debride the apical region of the root canal. The null hypothesis that there is no difference was tested. Root canals of matched pairs (N = 20) of extracted human teeth were prepared to an apical size of 36/.04 using Profile series 29/.04 rotary files (Dentsply Tulsa Dental, Tulsa, OK) with 6% sodium hypochlorite (NaOCl) irrigation. One tooth of each pair was randomly assigned to receive final irrigation with either VSS or conventional needle irrigation. The gauge of the needle (#30), the irrigation cycles (ie, 5 mL NaOCl, 5 mL 15% EDTA, and 5 mL NaOCl), the irrigant flow rate (5 mL/min), and needle depth placement (1 mm from the working length [WL]) were experimental constants. Serial sections were obtained at 1 and 3 mm from the WL, stained with hematoxylin-eosin, and viewed at 100× magnification for the presence of debris. The percentage of debris in the canal lumen after VSS or conventional needle irrigation was compared by using the Wilcoxon matched pairs test. There was significantly less debris in the VSS group compared with the conventional needle irrigation group at the 1-mm level (1.50% [VSS] vs 9.90% [conventional needle irrigation], P = .0001) and the 3-mm level (0.45% [VSS] vs 5.16% [conventional needle irrigation], P = .0014). The null hypothesis was rejected. Final irrigation with the VSS compared with conventional needle irrigation delivery resulted in significantly less debris present in root canals at 1 and 3 mm from the WL. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  6. Change of the Microstructure of ZnO Arrester Block by Lightning Surge Current and Ageing Test

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Bok Hee; Kang, Sung Man [Inha University (Korea)

    2000-07-01

    This paper deals with the change of the micro-structure of ZnO associated with lightning surge current and ageing test. In this work, a surge current generator which can produce 8/20 [{mu}s],6 [kA] impulse current is designed and fabricated to simulate the lightning impulse current. The residual voltage and leakage current flowing to ZnO blocks are observed. Also a compensation circuit was used in resistive current measurement. The micro-structures of ZnO arrester block were significantly changed by lightning surge current and accelerated temperature ageing test. (author). 6 refs., 7 figs., 1 tab.

  7. From solitary wave to traveling surge

    Institute of Scientific and Technical Information of China (English)

    宋礼庭

    1995-01-01

    The solution of kinetic Alfven wave under action of anomalous resistance has two branches: the slow wave, VPsurge and the fast wave VP>VA cosθ will be in a wave-broken state. Such traveling surge structure is a typical self-organization phenomenon and its wave form is determined by parameter β which represents the magnitude of resistance. High β leads to shock-like structure and low β to the appearance of some solitary waves in front of the shock. According to the study on solitary wave, shock wave and traveling surge in conjunction with self-organization of nonlinear dynamics, a general definition of wave can be given.

  8. Adaptive mesh refinement for storm surge

    KAUST Repository

    Mandli, Kyle T.

    2014-03-01

    An approach to utilizing adaptive mesh refinement algorithms for storm surge modeling is proposed. Currently numerical models exist that can resolve the details of coastal regions but are often too costly to be run in an ensemble forecasting framework without significant computing resources. The application of adaptive mesh refinement algorithms substantially lowers the computational cost of a storm surge model run while retaining much of the desired coastal resolution. The approach presented is implemented in the GeoClaw framework and compared to ADCIRC for Hurricane Ike along with observed tide gauge data and the computational cost of each model run. © 2014 Elsevier Ltd.

  9. Adaptive Mesh Refinement for Storm Surge

    CERN Document Server

    Mandli, Kyle T

    2014-01-01

    An approach to utilizing adaptive mesh refinement algorithms for storm surge modeling is proposed. Currently numerical models exist that can resolve the details of coastal regions but are often too costly to be run in an ensemble forecasting framework without significant computing resources. The application of adaptive mesh refinement algorithms substantially lowers the computational cost of a storm surge model run while retaining much of the desired coastal resolution. The approach presented is implemented in the \\geoclaw framework and compared to \\adcirc for Hurricane Ike along with observed tide gauge data and the computational cost of each model run.

  10. Disinfection of the root canal by sonic, ultrasonic and laser-activated irrigation

    NARCIS (Netherlands)

    van der Sluis, L.W.M.; Verhaagen, B.; Macedo, R.; Versluis, Andreas Michel; Cohenca, N.

    2014-01-01

    Irrigants are chemically inactivated after their reaction with the biofilm and therefore need to be mixed with fresh irrigants. Insight in the flow of the irrigant during a root canal treatment is crucial to understand the importance of the disinfection of the root canal system. This chapter

  11. Irrigation water quality assessments

    Science.gov (United States)

    Increasing demands on fresh water supplies by municipal and industrial users means decreased fresh water availability for irrigated agriculture in semi arid and arid regions. There is potential for agricultural use of treated wastewaters and low quality waters for irrigation but this will require co...

  12. Irrigation Systems. Student's Guide.

    Science.gov (United States)

    Amarillo Coll., TX.

    This guide is intended for use by individuals preparing for a career in commercial and residential irrigation. The materials included are geared toward students who have had some experience in the irrigation business; they are intended to be presented in 10 six-hour sessions. The first two sections deal with using this guide and preparing for the…

  13. Irrigation Systems. Instructor's Guide.

    Science.gov (United States)

    Amarillo Coll., TX.

    This guide is intended for use by licensed irrigators who wish to teach others how to design and install residential and commercial irrigation systems. The materials included in the guide have been developed under the assumption that the instructors who use it have little or no formal training as teachers. The first section presents detailed…

  14. Irrigation Without Waste

    Science.gov (United States)

    Shea, Kevin P.

    1975-01-01

    A new means of irrigation, called the drip or trickle system, has been proven more efficient and less wasteful than the current system of flood irrigation. As a result of this drip system, fertilizer-use efficiency is improved and crop yield, though never decreased, is sometimes increased in some crops. (MA)

  15. Influence of Closing Storm Surge Barrier on Extreme Water Levels and Water Exchange; The Limfjord, Denmark

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Quvang Harck; Bentzen, Thomas Ruby; Larsen, Torben;

    2014-01-01

    of the fjord. The reduction is obtained by blocking the ingoing flow with a sluice in due time before the storm surge peaks in the North Sea. In order to avoid problems with reduced water quality and salinity, the water exchange should be controlled by only keeping the sluice open for ingoing currents...... the increased risk of flooding in the estuary has revitalized the discussion whether this connection should be closed. In this paper, it is shown by numerical simulation that the establishment of a storm surge barrier across Thyborøn Channel can significantly reduce the peak water levels in the central...

  16. Mitigation of hurricane storm surge impacts: Modeling scenarios over wide continental shelves

    Science.gov (United States)

    Lima Rego, Joao; Li, Chunyan

    2010-05-01

    The improvement of present understanding of surge dynamics over wide and shallow shelves is vital for the improvement of our ability to forecast storm surge impacts to coastal regions, particularly the low-lying land areas that are most vulnerable to hurricane flooding (e.g. the Northern Gulf of Mexico, coastal Bangladesh, the Southeast China sea). Given the increase of global sea-surface temperature, both the total number and proportion of intense tropical cyclones have increased notably since 1970 (Emanuel, 2005; Nature). Therefore, more intense hurricanes may hit densely populated coastal regions, and this problem may be aggravated by the prospect of accelerated sea-level rise in the 21st century. This presentation offers a review of recent work on hurricane-induced storm surge. The finite-volume coastal ocean model ("FVCOM", by Chen et al., 2003; J. Atmos. Ocean Tech.) was applied to the storm surge induced by Hurricanes Rita and Ike along the coasts of Louisiana and Texas in 2005 and 2008, respectively, to study coastal storm surge dynamics. The sensitivity analysis of Rego and Li (2009; Geophys. Res. Lett.) demonstrated how stronger, wider or faster tropical cyclones would affect coastal flooding. Li, Weeks and Rego (2009; Geophys. Res. Lett) looked into how hurricane flooding and receding dynamics differ, concluding that the overland flow in the latter stage is of considerable importance. Rego and Li (2010; J. Geophys. Res.) showed how extreme events may result of a combination of non-extreme factors, by studying the nonlinear interaction of tide and hurricane surge. The ability of models to reproduce these extreme events and to proactive plan for damage reduction is covered in Rego and Li's (2010; J. Marine Syst.) study of how barrier island systems protect coastal bays from offshore surge propagation. Here we combine these results for a wider perspective on how hurricane flooding could be mitigated under changing conditions.

  17. Decision support for optimised irrigation scheduling

    NARCIS (Netherlands)

    Anastasiou, A.; Sawas, D.; Pasgianos, G.; Sigrimis, N.; Stanghellini, C.; Kempkes, F.L.K.

    2009-01-01

    The system, developed under the FLOW-AID (an FP6 project), is a farm level water management system of special value in situations where the water availability and quality is limited. This market-ready precision irrigation management system features new models, hardware and software. The hardware pla

  18. Numerical simulation of hydraulic performance on bidirectional flow channel of drip irrigation emitter using Fluent%基于Fluent软件的滴灌双向流流道灌水器水力性能数值模拟

    Institute of Scientific and Technical Information of China (English)

    田济扬; 白丹; 于福亮; 王新端; 郭霖

    2014-01-01

    The hydraulic performance of bidirectional flow channel is better than the hydraulic performance of labyrinth-channel, especially in 0.05-0.10 MPa. So bidirectional flow emitter can save more energy and the drip irrigation tube can be thinner, it can reduce investment cost and has good application in irrigation. In this study, numerical simulation method was used to accurately and efficiently design various kinds of channels of drip irrigation emitters. In order to improve the efficiency of research and reduce the cost of development, Fluent was used to simulate the bidirectional flow channel and analyze the mechanism of energy dissipation. A channel was designed within a reasonable range of structural parameters to study the grid partition and model selection. The results showed that unstructured grid was suitable for numerical simulation of bidirectional flow channel. Mesh cell sizes of 0.1 mm, 0.2 mm and 0.5 mm were chosen to calculate the flux of the channel under different pressures. Mesh cell size 0.2 mm under the numerical simulation was more accurate and efficient than the ones of 0.1 mm and 0.5 mm. In this paper, five turbulence models including standardk-ε, RNGk-ε, realizablek-ε, standardk-ω and SSTk-ω were compared. The simulating results of realizablek-ε and standardk-ω were better than that from other models. The correlation coefficients between the test results and the simulation values of these two models were 0.998 and 0.998, respectively, in 0.05-0.30 MPa. In 0.10-0.25 MPa, the simulation values were much closer to the test results. So Fluent can be used to simulate the water flow of the bidirectional flow channel and the simulation results had high precision. In addition, by orthogonal design method, we chose three key factors from the structural parameters and arranged nine experimental schemes to study the hydraulic performance and mechanism of energy dissipation. According to the main principle of the bidirectional flow channel, the flux

  19. Synthetic Fentanyl Fueling Surge in Overdose Deaths: CDC

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_160618.html Synthetic Fentanyl Fueling Surge in Overdose Deaths: CDC U.S. Surgeon ... News) -- Deaths from overdoses of the synthetic narcotic fentanyl have surged in recent years, U.S. health officials ...

  20. Irrigation in endodontics.

    Science.gov (United States)

    Haapasalo, M; Shen, Y; Wang, Z; Gao, Y

    2014-03-01

    Irrigation is a key part of successful root canal treatment. It has several important functions, which may vary according to the irrigant used: it reduces friction between the instrument and dentine, improves the cutting effectiveness of the files, dissolves tissue, cools the file and tooth, and furthermore, it has a washing effect and an antimicrobial/antibiofilm effect. Irrigation is also the only way to impact those areas of the root canal wall not touched by mechanical instrumentation. Sodium hypochlorite is the main irrigating solution used to dissolve organic matter and kill microbes effectively. High concentration sodium hypochlorite (NaOCl) has a better effect than 1 and 2% solutions. Ethylenediaminetetraacetic acid (EDTA) is needed as a final rinse to remove the smear layer. Sterile water or saline may be used between these two main irrigants, however, they must not be the only solutions used. The apical root canal imposes a special challenge to irrigation as the balance between safety and effectiveness is particularly important in this area. Different means of delivery are used for root canal irrigation, from traditional syringe-needle delivery to various machine-driven systems, including automatic pumps and sonic or ultrasonic energy.

  1. Approximate Nonlinear Modeling of Aircraft Engine Surge Margin Based on Equilibrium Manifold Expansion

    Institute of Scientific and Technical Information of China (English)

    LIU Xiaofeng; ZHAO Lei

    2012-01-01

    Stable operation of aircraft engine compressions is constrained by rotating surge.In this paper,an approximate nonlinear surge margin model of aircraft engine compression system by using equilibrium manifold is presented.Firstly,this paper gives an overview of the current state of modeling aerodynamic flow instabilities in engine compressors.Secondly,the expansion form of equilibrium manifold is introduced,and the choosing scheduling variable method is discussed.Then,this paper also gives the identification procedure of modeling the approximate nonlinear model.Finally,the modeling and simulations with high pressure (HP) compressor surge margin of the aircraft engine show that this real-time model has the same accuracy with the thermodynamic model,but has simpler structure and shorter computation time.

  2. Development of Strategies for Sustainable Irrigation Water Management in Russia

    Science.gov (United States)

    Zeyliger, Anatoly; Ermolaeva, Olga

    2013-04-01

    use of the appropriate irrigation technologies confined to a field scale and local environmental conditions. In presented contribution a case studies of large and small irrigation schemes based on sprinklers at Saratov Region will be discussed. Analyze is focused on the identification of main causes of groundwater logging, following soil salinization and impact to surrounding environment at irrigation areas. This analyze is based on plot and field scales experimentations as well as time series about 40 years long monitoring of ground water and soils. Main conclusion from this analyze accuses current irrigation practice at this region using high irrigation dozes & intensities as well as uniformity of water application within the irrigated perimeter promoting chain of processes starting by ponding of applied water at mezodepression of soil surface, preferential flow through out macropores-cracks, wormholes, or decayed root channels and groundwater rising. Special attention is done to simulate relationships between uniform technology of water application by sprinkler and spatial nonuniformity of moisture storage (zoning of high soil moisture in depressions) in soil and as consequence of infiltration capacity. Technological alternative aimed at reducing these problems is analysed by the use of SWAP model application to uniform and nonuniform irrigation water applications. Model results indicate that use nonuniform water application technology is increasing an irrigation efficiency, increasing yield and stopping rising of groundwater. ACKNOWLEDGMENTS. This study was financially supported by FP6 DESIRE project 037046

  3. A new on-line leakage current monitoring system of ZnO surge arresters

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Bok-Hee [Research Center for Next-Generation High Voltage and Power Technology, Inha University, 253 Yonghyun-dong, Nam-ku, Incheon 402-751 (Korea, Republic of)]. E-mail: bhlee@inha.ac.kr; Kang, Sung-Man [Research Center for Next-Generation High Voltage and Power Technology, Inha University, 253 Yonghyun-dong, Nam-ku, Incheon 402-751 (Korea, Republic of)

    2005-05-15

    This paper presents a new on-line leakage current monitoring system of zinc oxide (ZnO) surge arresters. To effectively diagnose the deterioration of ZnO surge arresters, a new algorithm and on-line leakage current detection device, which uses the time-delay addition method, for discriminating the resistive and capacitive currents was developed to use in the aging test and durability evaluation for ZnO arrester blocks. A computer-based measurement system of the resistive leakage current, the on-line monitoring device can detect accurately the leakage currents flowing through ZnO surge arresters for power frequency ac applied voltages. The proposed on-line leakage current monitoring device of ZnO surge arresters is more highly sensitive and gives more linear response than the existing devices using the detection method of the third harmonic leakage currents. Therefore, the proposed leakage current monitoring device can be useful for predicting the defects and performance deterioration of ZnO surge arresters in power system applications.

  4. Probabilistic modelling of sea surges in coastal urban areas

    Science.gov (United States)

    Georgiadis, Stylianos; Jomo Danielsen Sørup, Hjalte; Arnbjerg-Nielsen, Karsten; Nielsen, Bo Friis

    2016-04-01

    Urban floods are a major issue for coastal cities with severe impacts on economy, society and environment. A main cause for floods are sea surges stemming from extreme weather conditions. In the context of urban flooding, certain standards have to be met by critical infrastructures in order to protect them from floods. These standards can be so strict that no empirical data is available. For instance, protection plans for sub-surface railways against floods are established with 10,000 years return levels. Furthermore, the long technical lifetime of such infrastructures is a critical issue that should be considered, along with the associated climate change effects in this lifetime. We present a case study of Copenhagen where the metro system is being expanded at present with several stations close to the sea. The current critical sea levels for the metro have never been exceeded and Copenhagen has only been severely flooded from pluvial events in the time where measurements have been conducted. However, due to the very high return period that the metro has to be able to withstand and due to the expectations to sea-level rise due to climate change, reliable estimates of the occurrence rate and magnitude of sea surges have to be established as the current protection is expected to be insufficient at some point within the technical lifetime of the metro. The objective of this study is to probabilistically model sea level in Copenhagen as opposed to extrapolating the extreme statistics as is the practice often used. A better understanding and more realistic description of the phenomena leading to sea surges can then be given. The application of hidden Markov models to high-resolution data of sea level for different meteorological stations in and around Copenhagen is an effective tool to address uncertainty. For sea surge studies, the hidden states of the model may reflect the hydrological processes that contribute to coastal floods. Also, the states of the hidden Markov

  5. Active surge control of centrifugal compression systems : Theoretical and experimental results of drive actuation

    OpenAIRE

    Bøhagen, Bjørnar

    2007-01-01

    This thesis addresses modeling and active surge control of a simple compression system, using only the drive system of the compressor for actuation. Theoretical results are validated by experiments on a test rig that was built as a part of this work. Control laws are derived in two stages. First all system states, such as pressure mass flow and impeller speed, are assumed as available signals. All the resulting control laws require feedback from mass flow. However, transient measurement of th...

  6. 30 CFR 77.209 - Surge and storage piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Surge and storage piles. 77.209 Section 77.209... Installations § 77.209 Surge and storage piles. No person shall be permitted to walk or stand immediately above a reclaiming area or in any other area at or near a surge or storage pile where the...

  7. Numerical Evaluation of Storm Surge Indices for Public Advisory Purposes

    Science.gov (United States)

    Bass, B.; Bedient, P. B.; Dawson, C.; Proft, J.

    2016-12-01

    After the devastating hurricane season of 2005, shortcomings with the Saffir-Simpson Hurricane Scale's (SSHS) ability to characterize a tropical cyclones potential to generate storm surge became widely apparent. As a result, several alternative surge indices were proposed to replace the SSHS, including Powell and Reinhold's Integrated Kinetic Energy (IKE) factor, Kantha's Hurricane Surge Index (HSI), and Irish and Resio's Surge Scale (SS). Of the previous, the IKE factor is the only surge index to-date that truly captures a tropical cyclones integrated intensity, size, and wind field distribution. However, since the IKE factor was proposed in 2007, an accurate assessment of this surge index has not been performed. This study provides the first quantitative evaluation of the IKEs ability to serve as a predictor of a tropical cyclones potential surge impacts as compared to other alternative surge indices. Using the tightly coupled ADvanced CIRCulation and Simulating WAves Nearshore models, the surge and wave responses of Hurricane Ike (2008) and 78 synthetic tropical cyclones were evaluated against the SSHS, IKE, HSI and SS. Results along the upper TX coast of the Gulf of Mexico demonstrate that the HSI performs best in capturing the peak surge response of a tropical cyclone, while the IKE accounting for winds greater than tropical storm intensity (IKETS) provides the most accurate estimate of a tropical cyclones regional surge impacts. These results demonstrate that the appropriate selection of a surge index ultimately depends on what information is of interest to be conveyed to the public and/or scientific community.

  8. Projections of extreme storm surge levels along Europe

    Science.gov (United States)

    Vousdoukas, Michalis I.; Voukouvalas, Evangelos; Annunziato, Alessandro; Giardino, Alessio; Feyen, Luc

    2016-11-01

    Storm surges are an important coastal hazard component and it is unknown how they will evolve along Europe's coastline in view of climate change. In the present contribution, the hydrodynamic model Delft3D-Flow was forced by surface wind and atmospheric pressure fields from a 8-member climate model ensemble in order to evaluate dynamics in storm surge levels (SSL) along the European coastline (1) for the baseline period 1970-2000; and (2) during this century under the Representative Concentration Pathways RCP4.5 and RCP8.5. Validation simulations, spanning from 2008 to 2014 and driven by ERA-Interim atmospheric forcing, indicated good predictive skill (0.06 m relative sea level rise (RSLR), can be further enforced by an increase of the extreme SSL, which can exceed 30 % of the RSLR, especially for the high return periods and pathway RCP8.5. This implies that the combined effect could increase even further anticipated impacts of climate change for certain European areas and highlights the necessity for timely coastal adaptation and protection measures. The dataset is publicly available under this link: http://data.jrc.ec.europa.eu/collection/LISCOAST.

  9. Avoiding compressor surge during emergency shutdown hybridturbine systems

    Energy Technology Data Exchange (ETDEWEB)

    Pezzini, Paolo [University of Genova, Italy; Tucker, David [U.S. DOE; Traverso, Alberto [University of Genova, Italy

    2013-01-01

    A new emergency shutdown procedure for a direct-fired fuel cell turbine hybrid power system was evaluated using a hardware-based simulation of an integrated gasifier/fuel cell/turbine hybrid cycle (IGFC), implemented through the Hybrid Performance (Hyper) project at the National Energy Technology Laboratory, U.S. Department of Energy (NETL). The Hyper facility is designed to explore dynamic operation of hybrid systems and quantitatively characterize such transient behavior. It is possible to model, test, and evaluate the effects of different parameters on the design and operation of a gasifier/fuel cell/gas turbine hybrid system and provide a means of quantifying risk mitigation strategies. An open-loop system analysis regarding the dynamic effect of bleed air, cold air bypass, and load bank is presented in order to evaluate the combination of these three main actuators during emergency shutdown. In the previous Hybrid control system architecture, catastrophic compressor failures were observed when the fuel and load bank were cut off during emergency shutdown strategy. Improvements were achieved using a nonlinear fuel valve ramp down when the load bank was not operating. Experiments in load bank operation show compressor surge and stall after emergency shutdown activation. The difficulties in finding an optimal compressor and cathode mass flow for mitigation of surge and stall using these actuators are illustrated.

  10. Remote-sensing-based analysis of the 1996 surge of Northern Inylchek Glacier, central Tien Shan, Kyrgyzstan

    Science.gov (United States)

    Häusler, Hermann; Ng, Felix; Kopecny, Alexander; Leber, Diethard

    2016-11-01

    The evolution of Northern Inylchek Glacier and its proglacial lake - Upper Lake Merzbacher - during its 1996 surge and the surrounding decades is analyzed with remote sensing imagery. Overall retreat of the glacier from 1943 to 1996 enlarged the lake to 4 km long and ≈ 100 m deep. The surge in 1996 initiated between 12 September and 7 October and advanced the glacier by 3.7 km to override most of Upper Lake Merzbacher. The surge phase probably ended in December 1996 and involved mean flow velocities across the lower trunk of the glacier that reached 50 m d- 1 over a 32-day period. Water displaced by the surge from Upper Lake Merzbacher, totalling 1.5 × 108 m3 in volume, accelerated filling of Lower Lake Merzbacher downvalley and helped trigger this marginal ice-dammed lake to outburst in a jökulhlaup around late November/early December. The characteristics and duration of the surge render it as similar to temperate glacier surges elsewhere. It may have been facilitated by low basal friction caused by water-saturated sediments in the upper lake bed. Furthermore, bathymetric measurements show that the surge evacuated much sediment into the upper lake, causing its depth to reduce from 20 to 30 m in 1996 to 8 m by 2005 and 2 m by 2011; the corresponding deposition rates imply glacier-catchment specific mean sediment yields of 1.4 to 3.4 × 103 Mg km- 2 a- 1 in the years after the surge. Our study documents novel interactions within a cascade system of glaciers and lakes that exhibits surging and outburst-flood behavior.

  11. NUMERICAL STUDY OF WATER LEVEL FLUCTUATION IN BULL-HORN SURGE CHAMBER IN PIPE SYSTEM DURING WATERHAMMER

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The method of characteristics was adopted to analyze water level fluctuation existing in Bull-Horn surge chamber in reservoir-valve pipe system during waterhammer caused by valve closure operation. The Finite Difference Method (FDM) based on the method of characteristics was used to solve numerically the nonlinear two-parameter characteristic equations governing waterhammer. The finite fixed mesh was applied to obtaining the discrete form of the governing equations and discrete flow-field. The temporal trends of the y-directional flow, water level, velocity of water level and head difference for different heights of water in surge chamber, diameters of cylinder, cutting angles of surge chamber, lengths of horizontal cylinder and lengths of inclined cylinder were obtained under the condition that the air in surge chamber is compressible. The conclusions on water level fluctuation in Bull-Horn surge chamber were given based on the analyses of the obtained transient numerical results. These conclusions can play a guiding role in designing pipe system and executing surge suppression.

  12. ASPECTS OF DRIP IRRIGATION ON SLOPES

    Directory of Open Access Journals (Sweden)

    Oprea Radu

    2010-01-01

    Full Text Available Nowadays, water and its supply raise problems of strategic importance, of great complexity, being considered one of the keys to sustainable human development. Drip irrigation consists in the slow and controlled administration of water in the area of the root system of the plants for the purposes of fulfilling their physiological needs and is considered to be one of the variants of localized irrigation. Water is distributed in a uniform and slow manner, drop by drop, in a quantity and with a frequency that depend on the needs of the plant, thanks to the exact regulation of the water flow rate and pressure, as well as to the activation of the irrigation based on the information recorded by the tensiometer with regard to soil humidity. This method enables the exact dosage of the water quantity necessary in the various evolution stages of the plant, thus eliminating losses. By applying the irrigation with 5 liters of water per linear meter, at a 7 days interval, in the month of august, for a vine cultivated on a slope, in layers covered with black film and irrigated via dropping, soil humidity immediately after irrigation reaches its highest level, but within the limits of active humidity, on the line of the irrigation band. Three days later, the water content of the soil in the layer is relatively uniform, and, after this interval, it is higher in the points situated at the basis of the film. This technology of cultivation on slopes favors the accumulation, in the soil, of the water resulted from heavy rains and reduces soil losses as a result of erosion.

  13. Removal of human pathogenic viruses in a down-flow hanging sponge (DHS) reactor treating municipal wastewater and health risks associated with utilization of the effluent for agricultural irrigation.

    Science.gov (United States)

    Kobayashi, Naohiro; Oshiki, Mamoru; Ito, Toshihiro; Segawa, Takahiro; Hatamoto, Masashi; Kato, Tsuyoshi; Yamaguchi, Takashi; Kubota, Kengo; Takahashi, Masanobu; Iguchi, Akinori; Tagawa, Tadashi; Okubo, Tsutomu; Uemura, Shigeki; Harada, Hideki; Motoyama, Toshiki; Araki, Nobuo; Sano, Daisuke

    2017-03-01

    A down-flow hanging sponge (DHS) reactor has been developed as a cost-effective wastewater treatment system that is adaptable to local conditions in low-income countries. A pilot-scale DHS reactor previously demonstrated stable reduction efficiencies for chemical oxygen demand (COD) and ammonium nitrogen over a year at ambient temperature, but the pathogen reduction efficiency of the DHS reactor has yet to be investigated. In the present study, the reduction efficiency of a pilot-scale DHS reactor fed with municipal wastewater was investigated for 10 types of human pathogenic viruses (norovirus GI, GII and GIV, aichivirus, astrovirus, enterovirus, hepatitis A and E viruses, rotavirus, and sapovirus). DHS influent and effluent were collected weekly or biweekly for 337 days, and concentrations of viral genomes were determined by microfluidic quantitative PCR. Aichivirus, norovirus GI and GII, enterovirus, and sapovirus were frequently detected in DHS influent, and the log10 reduction (LR) of these viruses ranged from 1.5 to 3.7. The LR values for aichivirus and norovirus GII were also calculated using a Bayesian estimation model, and the average LR (±standard deviation) values for aichivirus and norovirus GII were estimated to be 1.4 (±1.5) and 1.8 (±2.5), respectively. Quantitative microbial risk assessment was conducted to calculate a threshold reduction level for norovirus GII that would be required for the use of DHS effluent for agricultural irrigation, and it was found that LRs of 2.6 and 3.7 for norovirus GII in the DHS effluent were required in order to not exceed the tolerable burden of disease at 10(-4) and 10(-6) disability-adjusted life years loss per person per year, respectively, for 95% of the exposed population during wastewater reuse for irrigation.

  14. Impacts of land cover changes on hurricane storm surge in the lower Chesapeake Bay

    Science.gov (United States)

    Denton, M.; Lawler, S.; Ferreira, C.

    2013-12-01

    The Chesapeake Bay is the largest estuary in the United States with more than 150 rivers draining into the bay's tidal wetlands. Coastal wetlands and vegetation play an important role in shaping the hydrodynamics of storm surge events by retaining water and slowing the propagation of storm surge. In this way coastal wetlands act as a natural barrier to inland flooding, particularly against less intense storms. Threats to wetlands come from both land development (residential or commercial/industrial) and sea level rise. The lower region of the Chesapeake Bay near its outlet is especially vulnerable to flooding from Atlantic storm surge brought in by hurricanes, tropical storms and nor'easters (e.g., hurricanes Isabel [2003] and Sandy [2012]). This region is also intensely developed with nearly 1.7 million residents within the greater Hampton Roads metropolitan area. Anthropogenic changes to land cover in the lower bay can directly impact basin drainage and storm surge propagation with impacts reaching beyond the immediate coastal zone to affect flooding in inland areas. While construction of seawall barriers around population centers may provide storm surge protection to a specifically defined area, these barriers deflect storm surge rather than attenuate it, underscoring the importance of wetlands. To analyze these impacts a framework was developed combining numerical simulations with a detailed hydrodynamic characterization of flow through coastal wetland areas. Storm surges were calculated using a hydrodynamic model (ADCIRC) coupled to a wave model (SWAN) forced by an asymmetric hurricane vortex model using the FEMA region 3 unstructured mesh (2.3 million nodes) under a High Performance Computing (HPC) environment. Multiple model simulations were performed using historical hurricanes data and hypothetical storms to compare the predicted storm surge inundation with various levels of wetland reduction and/or beach hardening. These data were combined and overlaid

  15. Earth Observation in aid of surge monitoring and forecasting: ESA's eSurge Project

    Science.gov (United States)

    Harwood, Phillip; Cipollini, Paolo; Snaith, Helen; Høyer, Jacob; Dwyer, Ned; Dunne, Declan; Stoffelen, Ad; Donlon, Craig

    2013-04-01

    The understanding and realistic modelling of surges supports both preparation and mitigation activities and should eventually bring enormous societal benefits, especially to some of the world's poorest countries. Earth Observation data from satellites have an important role to play in storm surge monitoring and forecasting, but the full uptake of these data by the users (such as environmental agencies and tidal prediction centres) must be first encouraged by showcasing their usefulness, and then supported by providing easy access. The European Space Agency has recognized the above needs and, through its Data User Element (DUE) programme, has initiated in 2011 the eSurge project, whose aims are: a) to contribute through Earth Observation to an integrated approach to storm surge, wave, sea-level and flood forecasting as part of a wider optimal strategy for building an improved forecast and warning capability for coastal inundation; and b) to increase the use of the advanced capabilities of ESA and other satellite data for storm surge applications. The project is led by Logica UK, with NOC (UK), DMI (Denmark), CMRC (Ireland) and KNMI (Netherlands) as scientific partners. eSurge aims to provide easy access to a wide range of relevant data for a range of historical surge events, as well as performing a series of experiments to demonstrate the value of this data, and running workshops and training courses to help users make use of the available data. The eSurge database of Earth Observation and in situ measurements for past surge events is now publicly available. In 2013 the project moves into its service demonstration phase, adding more data and events, including a demonstration near real time service. The project works closely with its users in order to meet their needs and to maximise the return of this data. A novel dataset provided by eSurge is coastal altimetry. Coastal altimetry has a prominent role to play as it measures directly the total water level envelope

  16. The use of coastal altimetry to support storm surge studies in project eSurge

    Science.gov (United States)

    Cipollini, P.; Harwood, P.; Snaith, H.; Vignudelli, S.; West, L.; Zecchetto, S.; Donlon, C.

    2012-04-01

    One of the most promising applications of the new field of coastal altimetry, i.e. the discipline aiming to recover meaningful estimates of geophysical parameters (sea level, significant wave height and wind speed) from satellite altimeter data in the coastal zone, is the study of storm surges. The understanding and realistic modelling of surges supports both preparation and mitigation activities and should eventually bring enormous societal benefits, especially to some of the world's poorest countries (like Bangladesh). Earth Observation data have an important role to play in storm surge monitoring and forecasting, but the full uptake of these data by users (such as environmental agencies and tidal prediction centres) must first be encouraged by showcasing their usefulness, and then supported by providing easy access. Having recognized the above needs, The European Space Agency has recently launched a Data User Element (DUE) project called eSurge. The main purposes of eSurge are a) to contribute to an integrated approach to storm surge, wave, sea-level and flood forecasting through Earth Observation, as part of a wider optimal strategy for building an improved forecast and early warning capability for coastal inundation; and b) to increase the use of the advanced capabilities of ESA and other satellite data for storm surge applications. The project is led by Logica UK, with NOC (UK), DMI (Denmark), CMRC (Ireland) and KNMI (Netherlands) as scientific partners. A very important component of eSurge is the development, validation and provision of dedicated coastal altimetry products, which is the focus of the present contribution. Coastal altimetry has a prominent role to play as it measures the total water level envelope directly, and this is one of the key quantities required by storm surge applications and services. But it can also provide important information on the wave field in the coastal strip, which helps the development of more realistic wave models that in

  17. Guiding Surge Reduction Strategies via Characterization of Coastal Surge Propagation and Internal Surge Generation within a Complex Bay/Estuary System, Galveston Bay, TX

    Science.gov (United States)

    Bass, B.; Torres, J.; Irza, N.; Bedient, P. B.; Dawson, C.; Proft, J.

    2015-12-01

    In this study, Hurricane Ike (2008) and a suite of synthetic storms are simulated in order to evaluate how different hurricane landfalls, wind intensities, and radius to maximum winds influence the surge response in complex semi-enclosed bays such as Galveston Bay, located along the Texas Gulf Coast. The Advanced CIRCulation and Simulating Waves Nearshore (ADCIRC+SWAN) models are employed to quantify surge in terms of its relative coastal contributions that propagate across barrier islands and tidal inlets and subsequently into Galveston Bay, the surge generated locally within the Bay itself, and the interaction between these coastal and local components of surge. Results from this research will further the current understanding of surge interactions in bay systems and guide coastal engineering surge reduction projects that need to consider multiple lines of defense to protect complex bay/estuary systems such as Galveston Bay, TX.

  18. Advances in Irrigation

    Science.gov (United States)

    Gardner, W. R.

    This is the first volume of Advances in Irrigation, a new serial publication by the publishers of Advances in Agronomy and Advances in Hydroscience and designed to follow the same format. The editor is a well-known researcher and writer on irrigation and related subjects and has assembled a collection of highly regarded and respected authors for the initial volume. The readership for this volume will probably be mainly specialists and students interested in irrigation and an occasional design engineer.The seven contributions in this volume fall roughly into two classes: research and practice. Three papers (“Conjunctive Use of Rainfall and Irrigation in Semi-arid Regions,” by Stewart and Musik, “Irrigation Scheduling Using Soil Moisture Measurements: Theory and Practice,” by G. S. and M. D. Campbell, and “Use of Solute Transport Models to Estimate Salt Balance Below Irrigated Cropland,” by Jury) cover topics that have been the subject of a number of reviews. The contributions here provide brief, well-written, and authoritative summaries of the chosen topics and serve as good introductions or reviews. They should lend themselves well to classroom use in various ways. They also should be helpful to the nonspecialist interested in getting a sense of the subject without going into great detail.

  19. Nonlinear chaotic model for predicting storm surges

    Directory of Open Access Journals (Sweden)

    M. Siek

    2010-09-01

    Full Text Available This paper addresses the use of the methods of nonlinear dynamics and chaos theory for building a predictive chaotic model from time series. The chaotic model predictions are made by the adaptive local models based on the dynamical neighbors found in the reconstructed phase space of the observables. We implemented the univariate and multivariate chaotic models with direct and multi-steps prediction techniques and optimized these models using an exhaustive search method. The built models were tested for predicting storm surge dynamics for different stormy conditions in the North Sea, and are compared to neural network models. The results show that the chaotic models can generally provide reliable and accurate short-term storm surge predictions.

  20. Hypergravity induced prolactin surge in female rats

    Science.gov (United States)

    Megory, E.; Oyama, J.

    1985-01-01

    Acute initial exposure to hypergravity (HG) was previously found to induce prolonged diestrous in rats, which was followed by return to normal estrous cycling upon more prolonged exposure to continuous HG. Bromergocryptine was found to prevent this prolonged diestrous. In this study it is found that in female rats 20 h of 3.14 G exposure (D-1 1200 h until D-2 0800 h) can induce prolactin surge at D-2 1600 h. Shorter exposure time (8 h), or exposure during a different part of the estrous cycle (19 h: from D-1 0700 h until D-2 0200 h) could not elicit this prolactin surge. Similar exposure of male rats of HG did not alter significantly their prolactin levels. It is possible that the hypothalamus of male and female rats responds differently to stimulation by HG.

  1. Liftoff of the 18 May 1980 surge of Mount St. Helens (USA) and the deposits left behind

    Science.gov (United States)

    Gardner, James E.; Andrews, Benjamin J.; Dennen, Robert

    2017-01-01

    The distance that ground-hugging pyroclastic density currents travel is limited partly by when they reverse buoyancy and liftoff into the atmosphere. It is not clear, however, what deposits are left behind by lofting flows. One current that was seen to liftoff was the surge erupted from Mount St. Helens on the morning of 18 May 1980. Before lofting, it had leveled a large area of thick forest (the blowdown zone). The outer edge of the devastated area—where trees were scorched but left standing (the scorched zone)—is where the surge is thought to have lifted off. Deposits in the outer parts of the blowdown and in the scorched zone were examined at 32 sites. The important finding is that the laterally moving surge traveled through the scorched zone, and hence, the change in tree damage does not mark the runout distance of the surge. Buoyancy reversal and liftoff are thus not preserved in the deposits where the surge lofted upwards. We propose, based on interpretation of eyewitness accounts and the impacts of the surge on trees and vehicles, that the surge consisted of a faster, dilute "overcurrent" and a slower "undercurrent," where most of the mass (and heat) was retained. Reasonable estimates for flow density and velocity show that dynamic pressure of the surge (i.e., its ability to topple trees) peaked near the base of the overcurrent. We propose that where the overcurrent began to liftoff, the height of peak dynamic pressure rose above the trees and stopped toppling them. The slower undercurrent continued forward, however, scorching trees, but lacked the dynamic pressure needed to topple them. Grain-size variations argue that it slowed from ˜30 m s-1 when it entered the scorched zone to ˜3 m s-1 at the far end.

  2. Runout distance and dynamic pressure of pyroclastic density currents: Evidence from 18 May 1980 blast surge of Mount St. Helens

    Science.gov (United States)

    Gardner, J. E.; Andrews, B. J.

    2016-12-01

    Pyroclastic density currents (flows and surges) are one of the most deadly hazards associated with volcanic eruptions. Understanding what controls how far such currents will travel, and how their dynamic pressure evolves, could help mitigate their hazards. The distance a ground hugging, pyroclastic density current travels is partly limited by when it reverses buoyancy and lifts off into the atmosphere. The 1980 blast surge of Mount St. Helens offers an example of a current seen to lift off. Before lofting, it had traveled up to 20 km and leveled more than 600 km3 of thick forest (the blowdown zone). The outer edge of the devastated area - where burned trees that were left standing (the singe zone) - is where the surge is thought to have lifted off. We recently examined deposits in the outer parts of the blowdown and in the singe zone at 32 sites. The important finding is that the laterally moving surge travelled into the singe zone, and hence the change in tree damage does not mark the run out distance of the ground hugging surge. Eyewitness accounts and impacts on trees and vehicles reveal that the surge consisted of a fast, dilute "overcurrent" and a slower "undercurrent", where most of the mass (and heat) was retained. Reasonable estimates for flow density and velocity show that dynamic pressure of the surge (i.e., its ability to topple trees) peaked near the base of the overcurrent. We propose that when the overcurrent began to lift off, the height of peak dynamic pressure rose above the trees and stopped toppling them. The slower undercurrent continued forward, burning trees but it lacked the dynamic pressure needed to topple them. Grain-size variations argue that it slowed from 30 m/s when it entered the singe zone to 3 m/s at the far end. Buoyancy reversal and liftoff are thus not preserved in the deposits where the surge lofted upwards.

  3. Probabilistic Storm Surge Hazard Assessment in Martinique

    Science.gov (United States)

    Krien, Yann; Dudon, Bernard; Sansorgne, Eliot; Roger, Jean; Zahibo, Narcisse; Roquelaure, Stevie

    2013-04-01

    Located at the center of the Lesser Antilles, Martinique is under the threat of hurricanes formed over the warm tropical waters of the Atlantic Ocean and Caribbean Sea. These events can be extremely costly in terms of human, property, and economic losses. Storm surge hazard studies are hence required to provide guidance to emergency managers and decision-makers. A few studies have been conducted so far in the French Lesser Antilles, but they mainly rely on scarce historical data of extreme sea levels or numerical models with coarse resolutions. Recent progress in statistical techniques for generating large number of synthetic hurricanes as well as availability of high-resolution topographic and bathymetric data (LIDAR) and improved numerical models enables us today to conduct storm surge hazard assessment studies with much more accuracy. Here we present a methodology to assess cyclonic surge hazard in Martinique both at regional and local scales. We first simulate the storm surges that would be induced by a large set of potential events generated by the statistical/deterministic models of Emanuel et al. [2006]. We use the ADCIRC-SWAN coupled models (Dietrich et al 2012) to simulate inundation inland with grid resolutions of up to 50-100m in the coastal area for the whole island.These models are validated against observations during past events such as hurricane Dean in 2007. The outputs can then be used in some specific sites to force higher resolution models for crisis management and local risk assessment studies. This work is supported by the INTERREG IV « Caribbean » program TSUNAHOULE.

  4. 微灌离心分离器内部流场分布数值模拟%Numerical simulation of flow field distribution in centrifugal separator for micro-irrigation

    Institute of Scientific and Technical Information of China (English)

    邱元锋; 孟戈; 罗金耀

    2015-01-01

    在缺水地区,利用高含沙水作为微灌水源的条件下,低浓度混合多相流模型已不能适用于微灌用离心分离器的数值模拟。该文以高含沙水作为微灌水源,结合离心分离器的结构参数,在流体力学基本方程基础上,通过网格划分和边界条件设定,采用有限体积法进行离散和求解,控制方程采用k-ε模型模拟分析了离心分离器的内部流场特征,并通过试验验证数值模拟成果,模拟值与试验实测值相对误差在10%以内,说明数值模拟采用的算法和模型是合理的。在试验验证的基础上,模拟分析了高含沙水为微灌水源的条件下,离心分离器的速度、湍动能以及静压分布,结果表明:离心分离器内速度分布主要有切向速度、轴向速度和径向速度,沿径向方向具有一定的对称性;离心分离器内湍动能分布具有一定的对称性,由轴中间向器壁两侧逐渐变小;静压分布具有一定的对称性性,由器壁两侧向轴中心逐渐减少。结果可为微灌用离心分离器特性参数的优化提供依据。%Centrifugal separator is one kind of filtration equipment that can separate the sediment from high-silt content water based on principles of rotational flow and centrifugal force. In recent years, research on numerical simulation of centrifugal separator is mostly in the fields of petroleum and chemical industry, and focuses on low concentration and mixture multiphase flow model. When using high-silt content water as micro-irrigation water source in water shortage areas, there will be high-silt content water near the centrifugal separator wall and underflow, in such case, low concentration and mixture multiphase flow model is not applicable to the numerical simulation of centrifugal separator that has used for micro-irrigation. Using high-silt content water as micro-irrigation water source, combined with the structure parameters of

  5. A new concept for glacial geological investigations of surges, based on High-Arctic examples (Svalbard)

    Science.gov (United States)

    Lønne, Ida

    2016-01-01

    Svalbard is a key area for the investigation of glacial surges, and almost two centuries worth of field observations exists from this region. Studies have shown that the course of a surge and the associated formation of landforms are strongly influenced by basinal factors, and that the broad range of variables involved can hamper interpretations and comparisons. Based on a review of surges in Svalbard, a new concept for glacial geological investigations has been developed that combines ice-flows, ice-front movements, and morphostratigraphy. The concept is comprised of the following four elements: 1) classification based on the configuration and characteristics of the receiving basin, 2) division of the surge cycle into six stages, 3) guidelines for morphological mapping, and 4) use of an allostratigraphic approach for interpreting ice-front movements. In this context, delineation of the active phase is critical, which include the history of terminus movements, and four main categories of receiving basins are recognized. These are (A) terrestrial basins with deformable substrates, (B) terrestrial basins with poorly deformable substrates, (C) shallow water basins, and (D) deep water basins. The ice-front movement history is reconstructed by coupling information from the proglacial moraines (syn-surge), the supraglacial moraines (post-surge), and the associated traces of meltwater to the surge stages (I-VI). This approach has revealed a critical relationship between the termination of the active phase and three morphological elements, namely, the maximum ice-front position, the maximum moraine extent and the youngest proglacial moraine, which are unique for each of the basins A-D. The concept is thus a novel and more precise approach for mapping the active phase and the active phase duration, as shown by the ∼12-year long surge of Fridtjovbreen, where stage I was 30 months (inception), stage II was 54 months (ice-front advance), stage III was 12 months (stillstand

  6. Flow state characteristics and fractal model parameters determination of quartz sand filter layer used in micro-irrigation%微灌石英砂滤层流态特性与分形阻力模型参数确定

    Institute of Scientific and Technical Information of China (English)

    李景海; 刘清霞; 黄修桥; 翟国亮; 韩启彪

    2015-01-01

    Quartz sand, one kind of porous media, is commonly used in micro-irrigation filter. Selecting optimal filtration speed and pressure drop of clean are important for design and operation of filters. In this study, fluid equation for porous media and fractal models were proposed to determine pressure drop of quartz sand layer. In order to facilitate flow zone division, we introduced dimensionless pressure drop into the original fluid equation of porous media. In this way, the empirical coefficients in fluid equation became meaningful. The dimensionless pressure drop is a linear function of Reynolds number, the changes in function curves indicates the changes in flow zones. Based on the dimensionless equation the flow pattern zone could be divided in combination with filtration tests. On the other hand, in the fractal model, the fractal dimensions of the curve and cross section were undetermined parameters. Their values could be determined by the empirical coefficient by comparing the fluid equation with fractal models. The method was demonstrated by a laboratory experiment conducted in Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinjiang, China in 2014. 3 kinds of quartz sand filter layer with different particle sizes were selected based on commonly used sizes in Xinjiang including equivalent sizes of 1.06, 1.2 and 1.5 mm. The sandy layer had a depth of 400 mm and porosity of 0.44. The flow characteristic of irrigation water in micro-irrigation filter with quartz sand was first analyzed and then the empirical coefficient of turbulent flow region was fitted by the experimental data. The parameters of the fractal model were determined, and the expression of fractal model of turbulent flow region was obtained. Using the values of fractal dimension of the curve and cross section in turbulent flow region, the fractal dimensions of curve and cross section in Forchheimer flow region was determined. And the expression of fractal model of

  7. Design and Characterization of a Centrifugal Compressor Surge Test Rig

    Directory of Open Access Journals (Sweden)

    Kin Tien Lim

    2011-01-01

    Full Text Available A detailed description of a new centrifugal compressor surge test rig is presented. The objective of the design and development of the rig is to study the surge phenomenon in centrifugal compression systems and to investigate a novel method of surge control by active magnetic bearing servo actuation of the impeller axial tip clearance. In this paper, we focus on the design, initial setup, and testing of the rig. The latter two include the commissioning of the rig and the experimental characterization of the compressor performance. The behavior of the compressor during surge is analyzed by driving the experimental setup into surge. Two fundamental frequencies, 21 Hz and 7 Hz, connected to the surge oscillation in the test rig are identified, and the observed instability is categorized according to the intensity of pressure fluctuations. Based on the test results, the excited pressure waves are clearly the result of surge and not stall. Also, they exhibit the characteristics of mild and classic surge instead of deep surge. Finally, the change in the compressor performance due to variation in the impeller tip clearance is experimentally examined, and the results support the potential of the tip clearance modulation for the control of compressor surge. This is the first such demonstration of the feasibility of surge control of a compressor using active magnetic bearings.

  8. Surge investigations in a radial single-stage blower with adjustable inlet guide vanes

    Energy Technology Data Exchange (ETDEWEB)

    Kryllowicz, W.; Horodko, L.; Hanausek, P.

    1996-12-31

    Experimental investigations of the influence of adjustable inlet guide vanes on the surge propagation in a radial single-stage blower system were carried out. The object of the investigations was a blower with a semi-open impeller with radially ended blades and a vaneless diffuser. The blower maximum pressure rate was {Pi} = 1.52 at the mass flow equal to m = 13.8 kg/s. The test instrumentation used consisted of classic probes and thermocouples and fast response semi-conductor pressure transducers located in flow path walls. Additionally, the noise level for different blower operating points was measured. These investigations made it possible to identify the mild and deep surge regions, the region of an inlet recirculation phenomenon as well as an inlet reverse flow phenomenon in the function of the IGV adjustment angle. (orig.)

  9. Basal processes beneath an Arctic glacier and their geomorphic imprint after a surge, Elisebreen, Svalbard

    Science.gov (United States)

    Christoffersen, Poul; Piotrowski, Jan A.; Larsen, Nicolaj K.

    2005-09-01

    The foreground of Elisebreen, a retreating valley glacier in West Svalbard, exhibits a well-preserved assemblage of subglacial landforms including ice-flow parallel ridges (flutings), ice-flow oblique ridges (crevasse-fill features), and meandering ridges (infill of basal meltwater conduits). Other landforms are thrust-block moraine, hummocky terrain, and drumlinoid hills. We argue in agreement with geomorphological models that this landform assemblage was generated by ice-flow instability, possibly a surge, which took place in the past when the ice was thicker and the bed warmer. The surge likely occurred due to elevated pore-water pressure in a thin layer of thawed and water-saturated till that separated glacier ice from a frozen substratum. Termination may have been caused by a combination of water drainage and loss of lubricating sediment. Sedimentological investigations indicate that key landforms may be formed by weak till oozing into basal cavities and crevasses, opening in response to accelerated ice flow, and into water conduits abandoned during rearrangement of the basal water system. Today, Elisebreen may no longer have surge potential due to its diminished size. The ability to identify ice-flow instability from geomorphological criteria is important in deglaciated terrain as well as in regions where ice dynamics are adapting to climate change.

  10. Controls of evaporative irrigation return flows in comparison to seawater intrusion in coastal karstic aquifers in northern Sri Lanka: Evidence from solutes and stable isotopes.

    Science.gov (United States)

    Chandrajith, Rohana; Diyabalanage, Saranga; Premathilake, K M; Hanke, Christian; van Geldern, Robert; Barth, Johannes A C

    2016-04-01

    Groundwater in Miocene karstic aquifers in the Jaffna Peninsula of Sri Lanka is an important resource since no other fresh water sources are available in the region. The subsurface is characterized by highly productive limestone aquifers that are used for drinking and agriculture purposes. A comprehensive hydrogeochemical study was carried out to reveal the processes affecting the groundwater quality in this region. Major and trace element composition and environmental isotope ratios of oxygen and hydrogen (δ(18)OH2O and δ(2)HH2O) were determined in 35 groundwater samples for this investigation. The ion abundance of groundwater in the region was characterized by an anion sequence order with HCO3->Cl->SO4->NO3-. For cations, average Na(+)+K(+) contents in groundwater exceeded those of Ca(2+)+Mg(2+) in most cases. Ionic relationships of major solutes indicated open system calcite dissolution while seawater intrusions are also evident but only close to the coast. The solute contents are enriched by agricultural irrigation returns and associated evaporation. This was confirmed by the stable isotope composition of groundwater that deviated from the local meteoric water line (LMWL) and formed its own regression line denoted as the local evaporation line (LEL). The latter can be described by δ(2)HH2O=5.8×δ(18)OH2O -- 2.9. Increased contents of nitrate-N (up to 5mg/L), sulfate (up to 430mg/L) and fluoride (up to 1.5mg/L) provided evidences for anthropogenic inputs of solutes, most likely from agriculture activities. Among trace elements Ba, Sr, As and Se levels in the Jaffna groundwater were higher compared to that of the dry zone metamorphic aquifers in Sri Lanka. Solute geochemistry and stable isotope evidences from the region indicates that groundwater in the area is mainly derived from local modern precipitation but modified heavily by progressive evaporative concentration rather than seawater intrusion.

  11. Friction distribution at the base of a surging glacier inferred from an inverse method

    Science.gov (United States)

    Gagliardini, O.; Jay-Allemand, M.; Gillet-Chaulet, F.

    2010-12-01

    The main objectives of this study is to investigate the basal conditions of a surging glacier. For that, we apply the inverse method proposed by Arthern and Gudmundsson (Journal of Glaciology, 2010). This method is based on an iterative descent algorithm numerically implemented in the finite element code Elmer/Ice. Neumann and Dirichlet problems are solved successively in order to minimize the cost function constructed as the norm of the difference between the basal velocities solutions of both problems. The method is applied to the Variegated glacier, a surge type glacier located in Alaska. We use measurements on this glacier carried out by Raymond and Harrison (Journal of Glaciology, 1988) during the quiescent stage of 1966-81 and the surge of 1982-83. Data contain surface velocities as well as the bed and surface topography along the central flow-line. In a first step, for each set of data obtained at different dates, we run the model diagnostically to solve for the basal drag coefficient in order to match the modelled horizontal surface velocities and the observed velocities. In a second step, inferred basal drag coefficient are analysed and then integrated in a transient simulation which cover the whole period of the data set, i.e. both quiescent and surge stages. Results show the contribution of basal sliding in the surge phenomenon and the modification of the basal condition from the quiescent to the surge stages. These modifications can be interpreted in term of changes in sub-glacial water pressure and runoff.

  12. Non-sustainable groundwater sustaining irrigation - a global assessment

    Science.gov (United States)

    Wada, Y.; van Beek, L. P. H.; Bierkens, M. F. P.

    2012-04-01

    Irrigated crops play a vital role in securing global food production. It is estimated that 17% of agricultural lands are irrigated, yet they account for 40% of the global food production, sustaining the livelihood of billions of people (Abdullah, 2006). At the same time, water used by irrigated crops (i.e., crop water demand) and irrigation water demand are responsible for about 70% of the global water withdrawal and account for about 90% of the global water consumption, i.e. water withdrawal minus return flow respectively. Water demand for irrigated crops can be met by three different sources: 1) green water, being water from local precipitation that is temporarily stored in the soil, 2) blue water, being surface freshwater available in rivers, lakes, reservoirs and wetlands, and renewable groundwater, and 3) non-renewable or non-sustainable groundwater and non-local water resources. Here, we quantify globally the amount of non-renewable groundwater abstraction to sustain current irrigation practice. We use the global hydrological model PCR-GLOBWB to simulate gross crop water demand for irrigated crops and available blue and green water to meet this demand. We downscale country statistics of groundwater abstraction by considering the part of net total water demand that cannot be met by surface freshwater. We subsequently confront these with simulated groundwater recharge including return flow from irrigation to estimate non-renewable groundwater abstraction. Results show that non-renewable groundwater abstraction contributes approximately 20% to the global gross irrigation water demand for the year 2000. The contribution of non-renewable groundwater abstraction to irrigation is largest in India (68 km3 yr-1) followed by Pakistan (35 km3/yr), USA (30 km3/yr), Iran (20 km3/yr), China (20 km3/yr), Mexico (10 km3/yr) and Saudi Arabia (10 km3/yr). Results also show that globally this contribution more than tripled from 75 to 234 km3/yr over the period 1960-2000. These

  13. [Endodontics in motion: new concepts, materials and techniques 3. The role of irrigants during root canal treatment].

    Science.gov (United States)

    van der Sluis, L W M

    2015-10-01

    The aims of root canal irrigation are the chemical dissolution or disruption and the mechanical detachment of pulp tissue, dentin debris and smear layer (instrumentation products), microorganisms (planktonic or biofilm) and their products from the root canal wall, their removal out of the root canal system and their chemical dissolution or disruption. Each of the endodontic irrigation systems has its own irrigant flow characteristics, which should fulfill these aims. Without flow (convection), the irrigant would have to be distributed through diffusion. This process is slow and depends on temperature and concentration gradients. On the other hand, convection is a faster and more efficient transport mechanism. During irrigant flow, frictional forces will occur, for example between the irrigant and the root canal wall (wall shear stress). These frictional forces have a mechanical cleaning effect on the root canal wall. These frictional forces are the result of the flow characteristics related to the different irrigation systems.

  14. Controls of evaporative irrigation return flows in comparison to seawater intrusion in coastal karstic aquifers in northern Sri Lanka: Evidence from solutes and stable isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Chandrajith, Rohana, E-mail: rohanac@pdn.ac.lk [Department of Geology, Faculty of Science, University of Peradeniya (Sri Lanka); Diyabalanage, Saranga [Department of Geology, Faculty of Science, University of Peradeniya (Sri Lanka); Premathilake, K.M. [Water Supply and Drainage Board, Telewala Road, Ratmalana (Sri Lanka); Hanke, Christian; Geldern, Robert van; Barth, Johannes A.C. [Friedrich-Alexander University Erlangen-Nuremberg (FAU), Department of Geography and Geosciences, GeoZentrum Nordbayern, Schlossgarten 5, 91054 Erlangen (Germany)

    2016-04-01

    Groundwater in Miocene karstic aquifers in the Jaffna Peninsula of Sri Lanka is an important resource since no other fresh water sources are available in the region. The subsurface is characterized by highly productive limestone aquifers that are used for drinking and agriculture purposes. A comprehensive hydrogeochemical study was carried out to reveal the processes affecting the groundwater quality in this region. Major and trace element composition and environmental isotope ratios of oxygen and hydrogen (δ{sup 18}O{sub H2O} and δ{sup 2}H{sub H2O}) were determined in 35 groundwater samples for this investigation. The ion abundance of groundwater in the region was characterized by an anion sequence order with HCO{sub 3}¯ > Cl¯ > SO{sub 4}¯ > NO{sub 3}¯. For cations, average Na{sup +}+K{sup +} contents in groundwater exceeded those of Ca{sup 2+} + Mg{sup 2+} in most cases. Ionic relationships of major solutes indicated open system calcite dissolution while seawater intrusions are also evident but only close to the coast. The solute contents are enriched by agricultural irrigation returns and associated evaporation. This was confirmed by the stable isotope composition of groundwater that deviated from the local meteoric water line (LMWL) and formed its own regression line denoted as the local evaporation line (LEL). The latter can be described by δ{sup 2}H{sub H2O} = 5.8 × δ{sup 18}O{sub H2O-–} 2.9. Increased contents of nitrate-N (up to 5 mg/L), sulfate (up to 430 mg/L) and fluoride (up to 1.5 mg/L) provided evidences for anthropogenic inputs of solutes, most likely from agriculture activities. Among trace elements Ba, Sr, As and Se levels in the Jaffna groundwater were higher compared to that of the dry zone metamorphic aquifers in Sri Lanka. Solute geochemistry and stable isotope evidences from the region indicates that groundwater in the area is mainly derived from local modern precipitation but modified heavily by progressive evaporative

  15. Climatic Controls on the Distribution of Surging Glaciers

    Science.gov (United States)

    Sevestre, H.; Benn, D.

    2012-12-01

    Surge-type glaciers are scattered in a non-random fashion, gathered in clusters in some glaciated regions. One group of clusters forms an Arctic and Sub-Arctic 'crescent', spanning from Alaska-Yukon, through Arctic Canada, West and East Greenland, Iceland, Svalbard and Novaya Zemlya. Another cluster occurs in western High Asia, including the Karakoram Mountains. Although several studies have assessed the influence of environmental controls on surging, so far none has provided a satisfactory explanation for the geographical location of these clusters. The distribution of such glaciers undoubtedly holds the keys of a better understanding on the controls on surging behaviour. For this study, two glacier populations are considered. First, a global inventory of glacier surges has been compiled, based on published observations, field reports and remote sensing studies. This digital database is structured in three tables, respectively providing information on the location and geometry of each surge-type glacier, surge dates and magnitude, and methodology employed at the time of observation. This global dataset is compared to the population of "non-surge-type glaciers" based on the Randolph Glacier Inventory version 2.0 excluding the inventoried surging glaciers. In both populations, glaciers are classified depending on their geometry and thermal regime. Downscaled climatic datasets are used to identify climatic envelopes associated with clusters of surging glaciers. We identified which environments are most prone to be associated to glacier surging, and examined the influence of these parameters on the surge cycle duration and character. These results emphasize the importance of external controls on surging (as against individual surges), and promote the need to study this behaviour in the frame of an energy-balance budget.

  16. SEDIMENT CONTROL FOR IRRIGATION INTAKES

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The analysis of the sediment problems in irrigation engineeringwas carried out, and the layout, the method as well as the effect of sediment control for irrigation intake structures in China were briefly introduced.

  17. Atlantic hurricane surge response to geoengineering

    Energy Technology Data Exchange (ETDEWEB)

    Moore, John C.; Grinsted, Aslak; Guo, Xiaoran; Yu, Xiaoyong; Jevrejeva, Svetlana; Rinke, Annette; Cui, Xuefeng; Kravitz, Ben; Lenton, Andrew; Watanabe, Shingo; Ji, Duoying

    2015-10-26

    Devastating Atlantic hurricanes are relatively rare events. However their intensity and frequency in a warming world may rapidly increase by a factor of 2-7 for each degree of increase in mean global temperature. Geoengineering by stratospheric sulphate aerosol injection cools the tropics relative to the polar regions, including the hurricane main development region in the Atlantic, suggesting that geoengineering may be an effective method of controlling hurricanes. We examine this hypothesis using 8 Earth System Model simulations of climate under the GeoMIP G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the RCP4.5 scenario. Global mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those in RCP4.5, but sulphate injection would have to double between 2020 and 2070 to balance RCP 4.5 to nearly 10 Tg SO2 yr-1, with consequent implications for damage to stratospheric ozone. We project changes in storm frequencies using a temperature-dependent Generalized Extreme Value statistical model calibrated by historical storm surges from 1923 and observed temperatures. The numbers of storm surge events as big as the one that caused the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this is only marginally statistically significant. However, when sea level rise differences at 2070 between RCP4.5 and geoengineering are factored in to coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5 year events and perhaps halved for 50 year surges.

  18. Atlantic hurricane surge response to geoengineering.

    Science.gov (United States)

    Moore, John C; Grinsted, Aslak; Guo, Xiaoran; Yu, Xiaoyong; Jevrejeva, Svetlana; Rinke, Annette; Cui, Xuefeng; Kravitz, Ben; Lenton, Andrew; Watanabe, Shingo; Ji, Duoying

    2015-11-10

    Devastating floods due to Atlantic hurricanes are relatively rare events. However, the frequency of the most intense storms is likely to increase with rises in sea surface temperatures. Geoengineering by stratospheric sulfate aerosol injection cools the tropics relative to the polar regions, including the hurricane Main Development Region in the Atlantic, suggesting that geoengineering may mitigate hurricanes. We examine this hypothesis using eight earth system model simulations of climate under the Geoengineering Model Intercomparison Project (GeoMIP) G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the Representative Concentration Pathway (RCP) 4.5 scenario. Global mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those temperature increases in the RCP4.5. However, sulfate injection would have to double (to nearly 10 teragrams of SO2 per year) between 2020 and 2070 to balance the RCP4.5, approximately the equivalent of a 1991 Pinatubo eruption every 2 y, with consequent implications for stratospheric ozone. We project changes in storm frequencies using a temperature-dependent generalized extreme value statistical model calibrated by historical storm surges and observed temperatures since 1923. The number of storm surge events as big as the one caused by the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this reduction is only marginally statistically significant. Nevertheless, when sea level rise differences in 2070 between the RCP4.5 and geoengineering are factored into coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5-y events and about halved for 50-y surges.

  19. An Investigation of the Basic Physics of Irrigation in Urology and the Role of Automated Pump Irrigation in Cystoscopy

    Directory of Open Access Journals (Sweden)

    Dwayne Chang

    2012-01-01

    Full Text Available Objective. To investigate the effects of height, external pressure, and bladder fullness on the flow rate in continuous, non-continuous cystoscopy and the automated irrigation fluid pumping system (AIFPS. Materials. Each experiment had two 2-litre 0.9% saline bags connected to a continuous, non-continuous cystoscope or AIFPS via irrigation tubing. Other equipment included height-adjustable drip poles, uroflowmetry devices, and model bladders. Methods. In Experiment 1, saline bags were elevated to measure the increment in flow rate. In Experiment 2, saline bags were placed under external pressures to evaluate the effect on flow rate. In Experiment 3, flow rate changes in response to variable bladder fullness were measured. Results. Elevating saline bags caused an increase in flow rates, however the increment slowed down beyond a height of 80 cm. Increase in external pressure on saline bags elevated flow rates, but inconsistently. A fuller bladder led to a decrease in flow rates. In all experiments, the AIFPS posted consistent flow rates. Conclusions. Traditional irrigation systems were susceptible to changes in height of irrigation solution, external pressure application, and bladder fullness thus creating inconsistent flow rates. The AIFPS produced consistent flow rates and was not affected by any of the factors investigated in the study.

  20. An Investigation of the Basic Physics of Irrigation in Urology and the Role of Automated Pump Irrigation in Cystoscopy

    Science.gov (United States)

    Chang, Dwayne; Manecksha, Rustom P.; Syrrakos, Konstantinos; Lawrentschuk, Nathan

    2012-01-01

    Objective. To investigate the effects of height, external pressure, and bladder fullness on the flow rate in continuous, non-continuous cystoscopy and the automated irrigation fluid pumping system (AIFPS). Materials. Each experiment had two 2-litre 0.9% saline bags connected to a continuous, non-continuous cystoscope or AIFPS via irrigation tubing. Other equipment included height-adjustable drip poles, uroflowmetry devices, and model bladders. Methods. In Experiment 1, saline bags were elevated to measure the increment in flow rate. In Experiment 2, saline bags were placed under external pressures to evaluate the effect on flow rate. In Experiment 3, flow rate changes in response to variable bladder fullness were measured. Results. Elevating saline bags caused an increase in flow rates, however the increment slowed down beyond a height of 80 cm. Increase in external pressure on saline bags elevated flow rates, but inconsistently. A fuller bladder led to a decrease in flow rates. In all experiments, the AIFPS posted consistent flow rates. Conclusions. Traditional irrigation systems were susceptible to changes in height of irrigation solution, external pressure application, and bladder fullness thus creating inconsistent flow rates. The AIFPS produced consistent flow rates and was not affected by any of the factors investigated in the study. PMID:22666130

  1. 滴灌双向流流道灌水器水力特性分析%Analysis on hydraulic performance of bidirectional flow channel of drip irrigation emitter

    Institute of Scientific and Technical Information of China (English)

    田济扬; 白丹; 任长江; 王新端

    2013-01-01

    滴灌双向流流道是一种新型滴灌灌水器流道。为了研究流道结构参数对水力特性的影响,分别以流态指数和流量系数为评价指标,取流道的9个主要结构参数为因素,采用均匀试验设计的方法,安排了12组试验方案。根据试验结果,应用多元回归计算方法,分别建立了流态指数和流量系数与9个结构参数之间的量化关系式,其相关系数分别为0.999和0.998,同时还用另外一组结构参数的试验方案验证了建立的量化关系式。T检验结果显示,9个主要结构参数对流态指数的影响均较显著,而V字形挡水件的张角α对其影响最大;出口宽度a、八字形分水件张角β对流量系数的影响较显著,而出口宽度a对其影响最大,为双向流流道的设计提供了参考。初步研究表明双向流流道的流态指数在0.40~0.47之间,其水力性能优良,结构简单,有一定应用前景。%The bidirectional flow channel is a new kind of channel for drip irrigation emitter, it has the advantages of simple structure, easy manufacturing and good hydraulic performance. The main working principle of the bidirectional flow channel is mixing the forward flow and the backward flow to enhance the effect of energy dissipation. The forward flow and backward flow are produced by splayed wall and V-shape wall in the channel. In order to study the effects of structural parameters on hydraulic performances, choosing 9 key factors from the structural parameters and arranging 12 experimental schemes to study flow index and flow coefficient. The experiments can obtain the inlet pressure of channel and the outlet flow rate. Each experimental scheme was set 3 repeats to make sure that the results are accurate. Based on the flux of bidirectional flow channel under different pressures, the flow index and flow coefficient can be obtained by using linear regression, and then regression equations can be built. The

  2. Analyzing the Potential Water Conservation Strategies: An Application to Irrigated Agriculture in the Texas Panhandle

    OpenAIRE

    Tewari, Rachna; Almas, Lal K.; Lust, David G.; Amosson, Stephen H.; Bretz, Fran E.

    2010-01-01

    Witnessing a rapid surge in irrigation requirements as well as the pressure on natural resources to augment production for satisfying grain demand for the growing human and livestock population, ground water supply in the Texas Panhandle reflects itself as a limiting yet indispensable factor. This study evaluates the effectiveness of eight potential water management strategies in terms of water savings, implementation costs as well as the regional impact of each policy on the agricultural eco...

  3. Analyzing the Potential Water Conservation Strategies: An Application to Irrigated Agriculture in the Texas Panhandle

    OpenAIRE

    Tewari, Rachna; Almas, Lal K.; Lust, David G.; Amosson, Stephen H.; Bretz, Fran E.

    2010-01-01

    Witnessing a rapid surge in irrigation requirements as well as the pressure on natural resources to augment production for satisfying grain demand for the growing human and livestock population, ground water supply in the Texas Panhandle reflects itself as a limiting yet indispensable factor. This study evaluates the effectiveness of eight potential water management strategies in terms of water savings, implementation costs as well as the regional impact of each policy on the agricultural eco...

  4. Glacier surge after ice shelf collapse.

    Science.gov (United States)

    De Angelis, Hernán; Skvarca, Pedro

    2003-03-07

    The possibility that the West Antarctic Ice Sheet will collapse as a consequence of ice shelf disintegration has been debated for many years. This matter is of concern because such an event would imply a sudden increase in sea level. Evidence is presented here showing drastic dynamic perturbations on former tributary glaciers that fed sections of the Larsen Ice Shelf on the Antarctic Peninsula before its collapse in 1995. Satellite images and airborne surveys allowed unambiguous identification of active surging phases of Boydell, Sjögren, Edgeworth, Bombardier, and Drygalski glaciers. This discovery calls for a reconsideration of former hypotheses about the stabilizing role of ice shelves.

  5. Fluid Lavage of Open Wounds (FLOW): A Multicenter, Blinded, Factorial Trial Comparing Alternative Irrigating Solutions and Pressures in Patients with Open Fractures

    Science.gov (United States)

    2013-10-01

    months, and 10 • patient’s illness beliefs with the Somatic Pre-Occupation and Coping ( SPOC ) questionnaire at 1 week and 6 weeks. 10a. SF-12 The SF...used in a sub-study comparing the test version to the validated version, which uses 3-level response options. 10c. SPOC The SPOC questionnaire...fractures SPOC : Somatic pre-occupation and coping questionnaire SSI: Surgical Site Infection FLOW February 19, 2013 Version: 6.0 Study Summary

  6. Planning for an Irrigation System.

    Science.gov (United States)

    Turner, J. Howard; Anderson, Carl L.

    The publication, with the aid of tables and colored illustrations and diagrams, presents information to help the farmer who is considering the installation of an irrigation system determine whether or not to irrigate, the type of system to use, and the irrigation cost and return on investment. Information is presented on the increase in yield to…

  7. Planning for an Irrigation System.

    Science.gov (United States)

    Turner, J. Howard; Anderson, Carl L.

    The publication, with the aid of tables and colored illustrations and diagrams, presents information to help the farmer who is considering the installation of an irrigation system determine whether or not to irrigate, the type of system to use, and the irrigation cost and return on investment. Information is presented on the increase in yield to…

  8. Application of the Viterbi Algorithm in Hidden Markov Models for Exploring Irrigation Decision Series

    Science.gov (United States)

    Andriyas, S.; McKee, M.

    2014-12-01

    Anticipating farmers' irrigation decisions can provide the possibility of improving the efficiency of canal operations in on-demand irrigation systems. Although multiple factors are considered during irrigation decision making, for any given farmer there might be one factor playing a major role. Identification of that biophysical factor which led to a farmer deciding to irrigate is difficult because of high variability of those factors during the growing season. Analysis of the irrigation decisions of a group of farmers for a single crop can help to simplify the problem. We developed a hidden Markov model (HMM) to analyze irrigation decisions and explore the factor and level at which the majority of farmers decide to irrigate. The model requires observed variables as inputs and the hidden states. The chosen model inputs were relatively easily measured, or estimated, biophysical data, including such factors (i.e., those variables which are believed to affect irrigation decision-making) as cumulative evapotranspiration, soil moisture depletion, soil stress coefficient, and canal flows. Irrigation decision series were the hidden states for the model. The data for the work comes from the Canal B region of the Lower Sevier River Basin, near Delta, Utah. The main crops of the region are alfalfa, barley, and corn. A portion of the data was used to build and test the model capability to explore that factor and the level at which the farmer takes the decision to irrigate for future irrigation events. Both group and individual level behavior can be studied using HMMs. The study showed that the farmers cannot be classified into certain classes based on their irrigation decisions, but vary in their behavior from irrigation-to-irrigation across all years and crops. HMMs can be used to analyze what factor and, subsequently, what level of that factor on which the farmer most likely based the irrigation decision. The study shows that the HMM is a capable tool to study a process

  9. Electrothermal model for complete metal-oxide surge arresters

    Energy Technology Data Exchange (ETDEWEB)

    Costa, E. Guedes da; Naidu, S.R. [UFPB, Dept. of Electrical Engineering, Campina Grande, PB (Brazil); Lima, A. Guedes de [CEFET-PB, Dept. of Mechanical Engineering, Joao Pessoa, PB (Brazil)

    2001-01-01

    A computational, electrothermal model for a complete metal-oxide surge arrester based on the implicit form of the finite-differences method is presented. The model is used to calculate the cooling curve after the application of overvoltages and the temperature variations during standard test. The model has been checked against experiments carried out on a test section and a complete surge arrester and the behaviour of a hypothetical surge arrester during standard tests simulated. (Author)

  10. Design and Characterization of a Centrifugal Compressor Surge Test Rig

    OpenAIRE

    2011-01-01

    A detailed description of a new centrifugal compressor surge test rig is presented. The objective of the design and development of the rig is to study the surge phenomenon in centrifugal compression systems and to investigate a novel method of surge control by active magnetic bearing servo actuation of the impeller axial tip clearance. In this paper, we focus on the design, initial setup, and testing of the rig. The latter two include the commissioning of the rig and the experimental characte...

  11. Investigating changes in basal conditions of Variegated Glacier prior to and during its 1982–1983 surge

    Directory of Open Access Journals (Sweden)

    M. Jay-Allemand

    2011-08-01

    Full Text Available Variegated Glacier (Alaska is known to surge periodically after a sufficient amount of cumulative mass balance is reached, but this observation is difficult to link with changes in the basal conditions. Here, using a 10-yr dataset, consisting of surface topography and surface velocity observations along a flow line for 25 dates, we have reconstructed the evolution of the basal conditions prior to and during the 1982–1983 surge. The model solves the full-Stokes problem along the central flow line using the finite element method. For the 25 dates of the dataset, the basal friction parameter distribution is inferred using the inverse method proposed by Arthern and Gudmundsson (2010. This method is here slightly modified by incorporating a regularisation term in the cost function to avoid short wavelength changes in the friction parameter. Our results indicate that dramatic changes in the basal conditions occurred between 1973 to 1983. Prior to the surge, periodic changes can be observed between winter and summer, with a regular increase of the sliding from 1973 to 1982. During the surge, the basal friction decreased dramatically and an area of very low friction moved from the upper part of the glacier to its terminus. Using a more complex friction law, these changes in basal sliding are then interpreted in terms of basal water pressure. Our results support that dramatic changes took place in the subglacial drainage system of Variegated Glacier, moving from a relatively efficient drainage system prior to the surge to an inefficient one during the surge. By reconstructing the water pressure evolution at the base of the glacier it is possible to propose a scenario for the hydrological history leading to the occurrence of a surge.

  12. Performance Comparison of the European Storm Surge Models and Chaotic Model in Forecasting Extreme Storm Surges

    Science.gov (United States)

    Siek, M. B.; Solomatine, D. P.

    2009-04-01

    Storm surge modeling has rapidly developed considerably over the past 30 years. A number of significant advances on operational storm surge models have been implemented and tested, consisting of: refining computational grids, calibrating the model, using a better numerical scheme (i.e. more realistic model physics for air-sea interaction), implementing data assimilation and ensemble model forecasts. This paper addresses the performance comparison between the existing European storm surge models and the recently developed methods of nonlinear dynamics and chaos theory in forecasting storm surge dynamics. The chaotic model is built using adaptive local models based on the dynamical neighbours in the reconstructed phase space of observed time series data. The comparison focused on the model accuracy in forecasting a recently extreme storm surge in the North Sea on November 9th, 2007 that hit the coastlines of several European countries. The combination of a high tide, north-westerly winds exceeding 50 mph and low pressure produced an exceptional storm tide. The tidal level was exceeded 3 meters above normal sea levels. Flood warnings were issued for the east coast of Britain and the entire Dutch coast. The Maeslant barrier's two arc-shaped steel doors in the Europe's biggest port of Rotterdam was closed for the first time since its construction in 1997 due to this storm surge. In comparison to the chaotic model performance, the forecast data from several European physically-based storm surge models were provided from: BSH Germany, DMI Denmark, DNMI Norway, KNMI Netherlands and MUMM Belgium. The performance comparison was made over testing datasets for two periods/conditions: non-stormy period (1-Sep-2007 till 14-Oct-2007) and stormy period (15-Oct-2007 till 20-Nov-2007). A scalar chaotic model with optimized parameters was developed by utilizing an hourly training dataset of observations (11-Sep-2005 till 31-Aug-2007). The comparison results indicated the chaotic

  13. Evaluating two irrigation controllers under subsurface drip irrigated tomato crop

    Directory of Open Access Journals (Sweden)

    Hussein M. Al-Ghobari

    2016-12-01

    Full Text Available Smart systems could be used to improve irrigation scheduling and save water under Saudi Arabia’s present water crisis scenario. This study investigated two types of evapotranspiration-based smart irrigation controllers, SmartLine and Hunter Pro-C2, as promising tools for scheduling irrigation and quantifying plants’ water requirements to achieve water savings. The effectiveness of these technologies in reducing the amount of irrigation water was compared with the conventional irrigation scheduling method as a control treatment. The two smart irrigation sensors were used for subsurface irrigation of a tomato crop (cv. Nema in an arid region. The results showed that the smart controllers significantly reduced the amount of applied water and increased the crop yield. In general, the Hunter Pro-C2 system saved the highest amount of water and produced the highest crop yield, resulting in the highest water irrigation efficiency compared with the SmartLine controller and the traditional irrigation schedule. It can be concluded that the application of advanced scheduling irrigation techniques such as the Hunter controller under arid conditions can realise economic benefits by saving large amounts of irrigation water.

  14. Simplified Storm Surge Simulations Using Bernstein Polynomials

    Science.gov (United States)

    Beisiegel, Nicole; Behrens, Jörn

    2016-04-01

    Storm surge simulations are vital for forecasting, hazard assessment and eventually improving our understanding of Earth system processes. Discontinuous Galerkin (DG) methods have recently been explored in that context, because they are locally mass-conservative and in combination with suitable robust nodal filtering techniques (slope limiters) positivity-preserving and well-balanced for the still water state at rest. These filters manipulate interpolation point values in every time step in order to retain the desirable properties of the scheme. In particular, DG methods are able to represent prognostic variables such as the fluid height at high-order accuracy inside each element (triangle). For simulations that include wetting and drying, however, the high-order accuracy will destabilize the numerical model because point values on quadrature points may become negative during the computation if they do not coincide with interpolation points. This is why the model that we are presenting utilizes Bernstein polynomials as basis functions to model the wetting and drying. This has the advantage that negative pointvalues away from interpolation points are prevented, the model is stabilized and no additional time step restriction is introduced. Numerical tests show that the model is capable of simulating simplified storm surges. Furthermore, a comparison of model results with third-order Bernstein polynomials with results using traditional nodal Lagrange polynomials reveals an improvement in numerical convergence.

  15. Hospital bioterrorism planning and burn surge.

    Science.gov (United States)

    Kearns, Randy D; Myers, Brent; Cairns, Charles B; Rich, Preston B; Hultman, C Scott; Charles, Anthony G; Jones, Samuel W; Schmits, Grace L; Skarote, Mary Beth; Holmes, James H; Cairns, Bruce A

    2014-01-01

    On the morning of June 9, 2009, an explosion occurred at a manufacturing plant in Garner, North Carolina. By the end of the day, 68 injured patients had been evaluated at the 3 Level I trauma centers and 3 community hospitals in the Raleigh/Durham metro area (3 people who were buried in the structural collapse died at the scene). Approximately 300 employees were present at the time of the explosion, when natural gas being vented during the repair of a hot water heater ignited. The concussion from the explosion led to structural failure in multiple locations and breached additional natural gas, electrical, and ammonia lines that ran overhead in the 1-story concrete industrial plant. Intent is the major difference between this type of accident and a terrorist using an incendiary device to terrorize a targeted population. But while this disaster lacked intent, the response, rescue, and outcomes were improved as a result of bioterrorism preparedness. This article discusses how bioterrorism hospital preparedness planning, with an all-hazards approach, became the basis for coordinated burn surge disaster preparedness. This real-world disaster challenged a variety of systems, hospitals, and healthcare providers to work efficiently and effectively to manage multiple survivors. Burn-injured patients served as a focus for this work. We describe the response, rescue, and resuscitation provided by first responders and first receivers as well as efforts made to develop burn care capabilities and surge capacity.

  16. Tide and skew surge independence: New insights for flood risk

    Science.gov (United States)

    Williams, Joanne; Horsburgh, Kevin J.; Williams, Jane A.; Proctor, Robert N. F.

    2016-06-01

    Storm surges are a significant hazard to coastal communities around the world, putting lives at risk and costing billions of dollars in damage. Understanding how storm surges and high tides interact is crucial for estimating extreme water levels so that we can protect coastal communities. We demonstrate that in a tidal regime the best measure of a storm surge is the skew surge, the difference between the observed and predicted high water within a tidal cycle. Based on tide gauge records spanning decades from the UK, U.S., Netherlands, and Ireland we show that the magnitude of high water exerts no influence on the size of the most extreme skew surges. This is the first systematic proof that any storm surge can occur on any tide, which is essential for understanding worst-case scenarios. The lack of surge generation dependency on water depth emphasizes the dominant natural variability of weather systems in an observation-based analysis. Weak seasonal relationships between skew surges and high waters were identified at a minority of locations where long-period changes to the tidal cycle interact with the storm season. Our results allow advances to be made in methods for estimating the joint probabilities of storm surges and tides.

  17. Auroral radio absorption and the westward travelling surge

    Energy Technology Data Exchange (ETDEWEB)

    Collis, P.N.; Korth, A.

    1983-11-01

    Measurements from a network of riometers during the passage of an auroral westward traveling surge are presented. These show that the energetic precipitation producing the radio absorption expands in an almost identical fashion to the softer precipitation associated with the visible surge; but it is delayed by about two minutes with respect to the surge. The delay is interpreted as a hardening of the precipitating electron spectrum as the surge goes by. Simultaneous observations of electrons at synchronous orbit are shown to support this conclusion. 24 references.

  18. Over 400 previously undocumented Svalbard surge-type glaciers identified

    Science.gov (United States)

    Farnsworth, Wesley R.; Ingólfsson, Ólafur; Retelle, Michael; Schomacker, Anders

    2016-07-01

    Identifying glaciers that exhibit surge-type behavior is important when using evidence of ice front fluctuations as a proxy for reconstructing past climate oscillations. This study identifies previously undocumented surge-type glaciers in Svalbard, based on the presence of crevasse squeeze ridges in glacier forelands. Crevasse squeeze ridges are landforms suggested to be unique to surging glacier land systems. Estimates vary greatly as to the actual percentage of surge-type glaciers in Svalbard, and consequently their distribution pattern is poorly understood. A detailed survey of recent (2008-2012), high-resolution aerial imagery from TopoSvalbard, provided by the Norwegian Polar Institute, allowed for a survey of all the glacier forelands in Svalbard. Before our study, 277 individual glaciers in Svalbard have been documented to exhibit surge behavior. By using crevasse squeeze ridges as indicators of surge behavior, we have identified 431 additional glaciers that have surged. We suggest that this is a modest value as the unique surge landforms were not visible in approximately one-third of the forelands with documented surge histories. Limits to the crevasse squeeze ridge technique are presented and potential controlling factors for crevasse squeeze ridge formation/preservation are discussed.

  19. On the magnitude and frequency of Karakoram Glacier surges

    Directory of Open Access Journals (Sweden)

    D. J. Quincey

    2013-10-01

    Full Text Available The return periods of Karakoram glacier surges are almost entirely unknown. Here, we present evidence of an historic surge of the Khurdopin Glacier that began in the mid-1970s and peaked in 1979. Measured surface displacements reached > 5 km yr–1, two orders of magnitude faster than during quiescence and twice as large as any previously recorded velocity in the region. The Khurdopin Glacier next surged in the late-1990s, equating to a return period of 20 yr. Surge activity in the region needs to be better understood if accurate mass balance assessments of Hindu-Kush–Karakoram–Himalaya glaciers are to be made.

  20. Review on Trickle Irrigation Application in Groundwater Irrigation Schemes

    Directory of Open Access Journals (Sweden)

    Prastowo

    2006-04-01

    Full Text Available The Government of Indonesia has developed groundwater irrigation schemes in some province e.g. East Java, Central Java, Yogyakarta, Wast Java, Bali, West Nusa Tenggara and East Nusa Tenggara. However, not all regions were able to optimally utilize it. The irrigation effeciency of groundwater irrigation scheme was about 59%, while the wells-pumping efficiencies were varied from 28 to 98 %. In thefuture, the irrigation effieciency should be increased to anticipate water deficit during dry season. The application of trickle irrigation in indonesia has not been widely developed. Although trickle system has been used, however, it is still limited for few commercial agribusinesses. Trickle irrigation systems have a prospect to be developed in some regions having limited water resources. For preliminary stage, the systems could be applied in groundwater irrigation schemes that have been developed either by farmers or government.

  1. Root canal irrigation

    NARCIS (Netherlands)

    L. van der Sluis; C. Boutsioukis; L.M. Jiang; R. Macedo; B. Verhaagen; M. Versluis

    2015-01-01

    The aims of root canal irrigation are the chemical dissolution or disruption and the mechanical detachment of pulp tissue, dentin debris and smear layer (instrumentation products), microorganisms (planktonic or biofilm), and their products from the root canal wall, their removal out of the root cana

  2. Greywater reuse for irrigation: effect on soil properties.

    Science.gov (United States)

    Travis, Micheal J; Wiel-Shafran, Alit; Weisbrod, Noam; Adar, Eilon; Gross, Amit

    2010-05-15

    A controlled study of the effect of greywater (GW) irrigation on soil properties was conducted. Containers of sand, loam and loess soils were planted with lettuce, and irrigated with fresh water, raw artificial GW or treated artificial GW. Greywater was treated using a recirculating vertical-flow constructed wetland. Soil samples were collected every 10 days for the 40-day duration of the study, and plant growth was measured. Soils were analysed for physicochemical and biological parameters to determine changes caused by the different treatments. It was demonstrated that raw artificial GW significantly increased the development of hydrophobicity in the sand and loam soils, as determined by water droplet penetration time. No significant changes were observed for the loess soil under all treatments. Observed hydrophobicity was correlated with increased oil and grease and surfactant concentrations in the soil. Zeta (zeta) potential of the soils was measured to determine changes in the soil particle surface properties as a result of GW irrigation. A significant change in zeta-potential (less negative) was observed in the raw artificial GW-irrigated sand, whereas no difference was observed in the loam or loess. Soils irrigated with fresh water or treated GW exhibited no increase in hydrophobicity. Fecal coliform bacteria were absent or <10 CFU g(-1) in soils irrigated with fresh water or treated GW, but at least 1 order of magnitude higher in raw artificial GW irrigated soils. Only in the last sampling event and only for the loess soil was plant growth significantly higher for fresh water irrigated vs. raw or treated GW irrigated soils. This study demonstrates that treated GW can be effectively irrigated without detrimental effects on soil or plant growth; however, raw GW may significantly change soil properties that can impact the movement of water in soil and the transport of contaminants in the vadose zone.

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  4. Storm surges formation in the White and Barents Seas

    Science.gov (United States)

    Arkhipkin, Victor; Dobrolyubov, Sergey; Korablina, Anastasia; Myslenkov, Stanislav

    2016-04-01

    Investigation of storm surges in the Arctic seas are of high priority in Russia due to the active development of offshore oil and gas, construction of facilities in the coastal zone, as well as for the safety of navigation. It is important to study the variability of surges, to predict this phenomena and subsequent economic losses, thus including such information into the Russian Arctic Development Program 2020. Surges in the White and Barents Seas are caused mainly by deep cyclones of two types: "diving" from the north (88% of all cyclones) and western. The average height of the storm surges in the White Sea is 0.6-0.9 m. An average duration of storm surges is about 80 hours. Mathematical modeling is used to analyze the characteristics of storm surges formation in the Dvina Bay of the White Sea, and in the Varandey village on the Barents Sea coast. Calculating storm surge heights in the White and Barents seas is performed using the ADCIRC model on an unstructured grid with a step from 20 km in the Barents Sea to 100 m in the White Sea. Unstructured grids allowed keeping small features of the coastline of the White and Barents seas, small islands and shallow banks, and assessing their impact on the development and transformation of wind-generated waves. The ADCIRC model used data of wind field reanalysis CFSv2. The storm surges were simulated for the time period from 1979 to 2010 and included scenarios with / without direct atmospheric pressure forcing, waves and tides. Numerical experiments have revealed distribution of storm surges in channels of the Northern Dvina River delta. The storm surges spreads in the model from the north-north-west of the Dvina Bay. As storm surge moves from the wellhead to the seaside estuary of the Northern Dvina (district Solombala), its height increases from 0.5 to 2 m. We also found a non-linear interaction of the surge and tide during the phase of surge destruction. This phenomenon is the highest in the period of low water, and the

  5. Surges Initiated by Newly-emerging Satellite Magnetic Fields

    Science.gov (United States)

    Wang, Jun-feng; Zhou, Tuan-hui; Ji, Hai-sheng

    2014-01-01

    On July 22, 2011 and in the active region NOAA 11259 there ap- peared the event of the ejection of solar atmospheric Hα surges. According to the full-disc Hα observations of the Big Bear Solar Observatory in United States, three consecutive surges at one and the same place in the north of the main spot of the active region were discovered. The trajectories of these three surges exhib- ited the figure of straight lines, and their integral configuration is like an inverted Eiffel Tower. The first two surges are quite similar, and in each of them there appeared two bright points in the northern part of the main spot. After several minutes, the surges appeared in the midst of bright points. When the bright- ness of the bright points attained the maximum value, the surges spouted out from the midst of bright points. And after reaching the maximum altitude, they quickly vanished. Before the ejection of the third surge took place, no bright points appeared. Besides, its maximal altitude is merely one half of that of the first two surges. Via a comparison with the SDO/HMI (Solar Dynamics Obser- vatory/Helioseismic and Magnetic Imager) data of radial magnetic fields, it is found that in more than one hour before the appearance of the first surge there emerged bipolar magnetic fields in the region of ejection. Besides, in several min- utes before the ejection of each Hα surge the magnetic fluxes of positive polarity diminished. Via our analysis it is found that there appeared reconnections be- tween the newly emerging satellite magnetic fields and the preexisting magnetic fields in the spot, and this caused the continuous ejections of Hα surges.

  6. Comparison of final irrigation techniques in removal of calcium hydroxide.

    Science.gov (United States)

    Yücel, Ali Çağın; Gürel, Melek; Güler, Eda; Karabucak, Bekir

    2013-12-01

    The aim of this study was to compare new irrigation systems with a conventional irrigation technique for the removal of inter-appointment calcium hydroxide [Ca(OH)2 ]. Forty-seven extracted human single-rooted teeth were instrumented, and Ca(OH)2 paste was placed into root canals by using a lentulo spiral at the apical third. Teeth were randomly divided into three groups according to different irrigation protocols using a 30-gauge slot-tipped needle, EndoVac system and ProUltra® PiezoFlow™ ultrasonic irrigation system. Scanning electron microscopic images of the selected root canal surfaces (cervical, middle and apical third) were evaluated using a 5-grade scale. The influence of the irrigation system was evaluated using a two-way analysis of variance test and Tukey's test. The EndoVac and PiezoFlow groups demonstrated the lowest scale values (cleanest canals); however, there was no statistical difference between these two groups. The conventional irrigation group exhibited significantly higher scores (P ultrasonic irrigation systems improved the removal of the intracanal medicament resulting in cleaner root canal walls. © 2011 The Authors. Australian Endodontic Journal © 2011 Australian Society of Endodontology.

  7. Simulating storm surge inundation and damage potential within complex port facilities

    Science.gov (United States)

    Mawdsley, Robert; French, Jon; Fujiyama, Taku; Achutan, Kamalasudhan

    2017-04-01

    Storm surge inundation of port facilities can cause damage to critical elements of infrastructure, significantly disrupt port operations and cause downstream impacts on vital supply chains. A tidal surge in December 2013 in the North Sea partly flooded the Port of Immingham, which handles the largest volume of bulk cargo in the UK including major flows of coal and biomass for power generation. This flooding caused damage to port and rail transport infrastructure and disrupted operations for several weeks. This research aims to improve resilience to storm surges using hydrodynamic modelling coupled to an agent-based model of port operations. Using the December 2013 event to validate flood extent, depth and duration, we ran a high resolution hydrodynamic simulation using the open source Telemac 2D finite element code. The underlying Digital Elevation Model (DEM) was derived from Environment Agency LiDAR data, with ground truthing of the flood defences along the port frontage. Major infrastructure and buildings are explicitly resolved with varying degrees of permeability. Telemac2D simulations are run in parallel and take only minutes on a single 16 cpu compute node. Inundation characteristics predicted using Telemac 2D differ from a simple Geographical Information System 'bath-tub' analysis of the DEM based upon horizontal application of the maximum water level across the port topography. The hydrodynamic simulation predicts less extensive flooding and more closely matches observed flood extent. It also provides more precise depth and duration curves. Detailed spatial flood depth and duration maps were generated for a range of tide and surge scenarios coupled to mean sea-level rise projections. These inundation scenarios can then be integrated with critical asset databases and an agent-based model of port operation (MARS) that is capable of simulating storm surge disruption along wider supply chains. Port operators are able to act on information from a particular

  8. Will oscillating wave surge converters survive tsunamis?

    Directory of Open Access Journals (Sweden)

    L. O’Brien

    2015-07-01

    Full Text Available With an increasing emphasis on renewable energy resources, wave power technology is becoming one of the realistic solutions. However, the 2011 tsunami in Japan was a harsh reminder of the ferocity of the ocean. It is known that tsunamis are nearly undetectable in the open ocean but as the wave approaches the shore its energy is compressed, creating large destructive waves. The question posed here is whether an oscillating wave surge converter (OWSC could withstand the force of an incoming tsunami. Several tools are used to provide an answer: an analytical 3D model developed within the framework of linear theory, a numerical model based on the non-linear shallow water equations and empirical formulas. Numerical results show that run-up and draw-down can be amplified under some circumstances, leading to an OWSC lying on dry ground!

  9. A MICROGAP SURGE ABSORBER FABRICATED USING CONVENTIONAL SEMICONDUCTOR TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    李宏; 阮航宇

    2001-01-01

    A new type microgap surge absorber fabricated by only semiconductor technique has in it a special structure silicon chip which forms microgaps for gas discharge with electrodes, and has advantages such as small size, low cost, suitability for mass production besides the desirable characteristics that common microgap surge absorbers have. Applications of this absorber in communication facilities are discussed.

  10. Scenario-based Storm Surge Vulnerability Assessment of Catanduanes

    Science.gov (United States)

    Suarez, J. K. B.

    2015-12-01

    After the devastating storm surge effect of Typhoon Haiyan, the public recognized an improved communication about risks, vulnerabilities and what is threatened by storm surge. This can be provided by vulnerability maps which allow better visual presentations and understanding of the risks and vulnerabilities. Local implementers can direct the resources needed for protection of these areas. Moreover, vulnerability and hazard maps are relevant in all phases of disaster management designed by the National Disaster Risk Reduction Council (NDRRMC) - disaster preparedness, prevention and mitigation and response and recovery and rehabilitation. This paper aims to analyze the vulnerability of Catanduanes, a coastal province in the Philippines, to storm surges in terms of four parameters: population, built environment, natural environment and agricultural production. The vulnerability study relies on the storm surge inundation maps based on the Department of Science and Technology Nationwide Operational Assessment of Hazards' (DOST-Project NOAH) proposed four Storm Surge Advisory (SSA) scenarios (1-2, 3, 4, and 5 meters) for predicting storm surge heights. To determine total percent affected for each parameter elements, an overlay analysis was performed in ArcGIS Desktop. Moreover, vulnerability and hazard maps are generated as a final output and a tool for visualizing the impacts of storm surge event at different surge heights. The result of this study would help the selected province to know their present condition and adapt strategies to strengthen areas where they are found to be most vulnerable in order to prepare better for the future.

  11. Predicting Storm Surges: Chaos, Computational Intelligence, Data Assimilation, Ensembles

    NARCIS (Netherlands)

    Siek, M.B.L.A.

    2011-01-01

    Accurate predictions of storm surge are of importance in many coastal areas. This book focuses on data-driven modelling using methods of nonlinear dynamics and chaos theory for predicting storm surges. A number of new enhancements are presented: phase space dimensionality reduction, incomplete time

  12. EVALUATION OF SELF COMPENSATING EMITTERS IRRIGATING WITH SALINE WATER: PART II: PROCESS CAPABILITY INDEX

    OpenAIRE

    Silva,Patrícia F. da; Dantas Neto, José; Vera L. A. de Lima; Santos,Delfran B. Dos; Ribeiro,Pedro H. P.

    2016-01-01

    ABSTRACT The use of tools such as process capability index for irrigation aims to observe how this irrigation is adequate in terms of quality. The aim of the study was analyzing the Christiansen uniformity coefficient and the flow of a drip irrigation system with self-compensating emitters under water different salt concentrations, using the process capability index. The research was conducted in a greenhouse at the Federal University of Campina Grande (UFCG). The experimental design was a ra...

  13. Spectrophotometric determination of irrigant extrusion using passive ultrasonic irrigation, EndoActivator, or syringe irrigation.

    Science.gov (United States)

    Rodríguez-Figueroa, Carolina; McClanahan, Scott B; Bowles, Walter R

    2014-10-01

    Sodium hypochlorite (NaOCl) irrigation is critical to endodontic success, and several new methods have been developed to improve irrigation efficacy (eg, passive ultrasonic irrigation [PUI] and EndoActivator [EA]). Using a novel spectrophotometric method, this study evaluated NaOCl irrigant extrusion during canal irrigation. One hundred fourteen single-rooted extracted teeth were decoronated to leave 15 mm of the root length for each tooth. Cleaning and shaping of the teeth were completed using standardized hand and rotary instrumentation to an apical file size #40/0.04 taper. Roots were sealed (not apex), and 54 straight roots (n = 18/group) and 60 curved roots (>20° curvature, n = 20/group) were included. Teeth were irrigated with 5.25% NaOCl by 1 of 3 methods: passive irrigation with needle, PUI, or EA irrigation. Extrusion of NaOCl was evaluated using a pH indicator and a spectrophotometer. Standard curves were prepared with known amounts of irrigant to quantify amounts in unknown samples. Irrigant extrusion was minimal with all methods, with most teeth showing no NaOCl extrusion in straight or curved roots. Minor NaOCl extrusion (1-3 μL) in straight roots or curved roots occurred in 10%-11% of teeth in all 3 irrigant methods. Two teeth in both the syringe irrigation and the EA group extruded 3-10 μL of NaOCl. The spectrophotometric method used in this study proved to be very sensitive while providing quantification of the irrigant levels extruded. Using the PUI or EA tip to within 1 mm of the working length appears to be fairly safe, but apical anatomy can vary in teeth to allow extrusion of irrigant. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  14. Irrigation mitigates against heat extremes

    Science.gov (United States)

    Thiery, Wim; Fischer, Erich; Visser, Auke; Hirsch, Annette L.; Davin, Edouard L.; Lawrence, Dave; Hauser, Mathias; Seneviratne, Sonia I.

    2017-04-01

    Irrigation is an essential practice for sustaining global food production and many regional economies. Emerging scientific evidence indicates that irrigation substantially affects mean climate conditions in different regions of the world. Yet how this practice influences climate extremes is currently unknown. Here we use gridded observations and ensemble simulations with the Community Earth System Model to assess the impacts of irrigation on climate extremes. While the influence of irrigation on annual mean temperatures is limited, we find a large impact on temperature extremes, with a particularly strong cooling during the hottest day of the year (-0.78 K averaged over irrigated land). The strong influence on hot extremes stems from the timing of irrigation and its influence on land-atmosphere coupling strength. Together these effects result in asymmetric temperature responses, with a more pronounced cooling during hot and/or dry periods. The influence of irrigation is even more pronounced when considering subgrid-scale model output, suggesting that local effects of land management are far more important than previously thought. Finally we find that present-day irrigation is partly masking GHG-induced warming of extreme temperatures, with particularly strong effects in South Asia. Our results overall underline that irrigation substantially reduces our exposure to hot temperature extremes and highlight the need to account for irrigation in future climate projections.

  15. Asian irrigation, African rain: Remote impacts of irrigation

    Science.gov (United States)

    Vrese, Philipp; Hagemann, Stefan; Claussen, Martin

    2016-04-01

    Irrigation is not only vital for global food security but also constitutes an anthropogenic land use change, known to have strong effects on local hydrological and energy cycles. Using the Max Planck Institute for Meteorology's Earth System Model, we show that related impacts are not confined regionally but that possibly as much as 40% of the present-day precipitation in some of the arid regions in Eastern Africa are related to irrigation-based agriculture in Asia. Irrigation in South Asia also substantially influences the climate throughout Southeast Asia and China via the advection of water vapor and by altering the Asian monsoon. The simulated impact of irrigation on remote regions is sensitive to the magnitude of the irrigation-induced moisture flux. Therefore, it is likely that a future extension or decline of irrigated areas due to increasing food demand or declining fresh water resources will also affect precipitation and temperatures in remote regions.

  16. Switching Surge Analysis of Vacuum Circuit Breaker using EMTP

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ik Mo; Kim, Ji Hong [Hyundai Heavy Industry, Mechatronics Research Institute (Korea)

    2000-07-01

    The first objective of this study is to set up the switching surge analysis method in motor driving distribution system. The simplified model which can simulate the motor energization and circuit breaker re-ignitions, and each circuit element model is presented in this paper. The second objective is to calculate the quantity of surge over-voltage in real nuclear power station. And the surge suppressing measures are verified on the simulation basis. It is clarified that most cases are not satisfactory to meet the IEEE standard 522-1992 without using surge suppressing measures. In cases that the surge arrester are installed in distribution board at the load side of circuit breaker. The IEEE specification is fully met. (author). 6 refs., 4 figs., 3 tabs.

  17. Investigation of Surge Behavior in a Micro Centrifugal Compressor

    Institute of Scientific and Technical Information of China (English)

    Shimpei MIZUKI; Yuichiro ASAGA; Yushi ONO; Hoshio TSUJITA

    2006-01-01

    This paper reports the experimental and theoretical study of the surge occurred in prototyping an ultra micro centrifugal compressor. As the first step, the 10 times size model of an ultra micro centrifugal compressor having the 40 mm outer diameter was designed and manufactured. The detailed experimental investigations for the transient behavior of surge with several different values of B parameter were carried out. The experimental results during the surge were compared with those obtained by the non-linear lumped parameter theory in order to validate the effectiveness of the theoretical surge model for the micro centrifugal compressor. As a result, the quite different behavior of the surge appeared for the different values of B both in the experiment and in the analysis.

  18. Application of short-data methods on extreme surge levels

    Science.gov (United States)

    Feng, X.

    2014-12-01

    Tropical cyclone-induced storm surges are among the most destructive natural hazards that impact the United States. Unfortunately for academic research, the available time series for extreme surge analysis are very short. The limited data introduces uncertainty and affects the accuracy of statistical analyses of extreme surge levels. This study deals with techniques applicable to data sets less than 20 years, including simulation modelling and methods based on the parameters of the parent distribution. The verified water levels from water gauges spread along the Southwest and Southeast Florida Coast, as well as the Florida Keys, are used in this study. Methods to calculate extreme storm surges are described and reviewed, including 'classical' methods based on the generalized extreme value (GEV) distribution and the generalized Pareto distribution (GPD), and approaches designed specifically to deal with short data sets. Incorporating global-warming influence, the statistical analysis reveals enhanced extreme surge magnitudes and frequencies during warm years, while reduced levels of extreme surge activity are observed in the same study domain during cold years. Furthermore, a non-stationary GEV distribution is applied to predict the extreme surge levels with warming sea surface temperatures. The non-stationary GEV distribution indicates that with 1 Celsius degree warming in sea surface temperature from the baseline climate, the 100-year return surge level in Southwest and Southeast Florida will increase by up to 40 centimeters. The considered statistical approaches for extreme surge estimation based on short data sets will be valuable to coastal stakeholders, including urban planners, emergency managers, and the hurricane and storm surge forecasting and warning system.

  19. Active control of surge in centrifugal compressors using magnetic thrust bearing actuation

    Science.gov (United States)

    Sanadgol, Dorsa

    This research presents a new method for active surge control in centrifugal compressors with unshrouded impellers using a magnetic thrust bearing to modulate the impeller tip clearance. Magnetic bearings offer the potential for active control of flow instabilities. This capability is highly dependent on the sensitivity of the compressor characteristics to blade tip clearance. If the position of the shaft can be actuated with sufficient authority and speed, the induced pressure modulation makes control of surge promising. The active nature of the magnetic bearing system makes the real-time static and dynamic positioning of the rotor and therefore modulation of the impeller tip clearance possible. A theoretical model is first established that describes the sensitivity of the centrifugal compressor characteristic curve to tip clearance variations induced by axial motion of the rotor. Results from simulation of the nonlinear model for a single stage high-speed centrifugal compressor show that using the proposed control method, mass flow and pressure oscillations associated with compressor surge are quickly suppressed with acceptable tip clearance excursions, typically less than 20% of the available clearance. It is shown that it is possible to produce adequate axial excursions in the clearance between the impeller blades and the adjacent stationary shroud using a magnetic thrust bearing with practical levels of drive voltage. This surge control method would allow centrifugal compressors to reliably and safely operate with a wider range than is currently done in the field. The principal advantage of the proposed approach over conventional surge control methods lies in that, in machines already equipped with magnetic bearing, the method can potentially be implemented by simply modifying controller software. This dispenses with the need to introduce additional hardware, permitting adaptation of existing machinery at virtually no cost. In addition, since the controller is

  20. Sedimentological recorders of the 2013 Typhoon Haiyan storm surge from contrasting Philippine coastal landscapes

    Science.gov (United States)

    Soria, J. L.; Switzer, A.; Siringan, F. P.; Pilarczyk, J.; Li, L.

    2016-12-01

    Typhoon Haiyan in 2013 was an extremely intense and fast moving typhoon. It claimed more than 6000 lives, caused widespread damage, and affected more than 16 million people along its path in central Philippines. Overwash associated with the 5 to 8 m storm surge of Typhoon Haiyan also left behind a variety of geomorphic and sedimentological imprints, which provide a valuable dataset for modern storm deposits in different landform settings. Here we only present a synthesis of the sedimentological imprints from sites that span clastic, mixed clastic-carbonate, and non-clastic carbonate coasts, and were affected by contrasting surge mechanisms. On the sheltered clastic coast where overwash was dominated by wind-induced setup surge, the overwash sediments occur as a sand unit of no more than 20 cm near the shore, and then spread into sub-cm thin sandsheet that blanket pre-Haiyan soil surfaces up to 1.6 km inland. Thicker sections of the overwash sand exhibit sharp depositional contacts, planar stratification, and generally coarsen upward and fine landward. On the mixed clastic-carbonate coast, the Typhoon Haiyan deposits are generally thin (coast that was affected by a wave-dominated setup surge, the overwash sediments include two distinct assemblages: carbonate boulders now occupying the reef flat surface, and a sand sheet that blanketed the coastal plain up to 300 m distance inland. On the open coast, inverse modeling of flow velocities derived from boulder dimensions, sediment thickness, and grain size distributions indicate that the storm surge travelled across the wide reef flat and inundated the coast with flow velocities exceeding 4 ms-1. The sediment data support the tsunami-like surge characteristics of Haiyan, and although Haiyan's overwash sediments are clearly representative of Philippine modern storm deposits, they should however be used with caution in the interpretation of the geologic record. This cautionary note highlights the continuing issue of

  1. Effect of low‐cost irrigation methods on microbial contamination of lettuce irrigated with untreated wastewater

    National Research Council Canada - National Science Library

    Keraita, Bernard; Konradsen, Flemming; Drechsel, Pay; Abaidoo, Robert C

    2007-01-01

    Objective  To assess the effectiveness of simple irrigation methods such as drip irrigation kits, furrow irrigation and use of watering cans in reducing contamination of lettuce irrigated with polluted water...

  2. Making the user visible: analysing irrigation practices and farmers’ logic to explain actual drip irrigation performance

    NARCIS (Netherlands)

    Benouniche, M.; Kuper, M.; Hammani, A.; Boesveld, H.

    2014-01-01

    The actual performance of drip irrigation (irrigation efficiency, distribution uniformity) in the field is often quite different from that obtained in experimental stations. We developed an approach to explain the actual irrigation performance of drip irrigation systems by linking measured

  3. Induced heterogeneity of soil water content and chemical properties by treated wastewater irrigation and its reclamation by freshwater irrigation

    Science.gov (United States)

    Rahav, Matan; Brindt, Naaran; Yermiyahu, Uri; Wallach, Rony

    2017-06-01

    The recognition of treated wastewater (TWW) as an alternative water resource is expanding in areas with a shortage of freshwater (FW) resources. Today, most orchards in Israel are irrigated with TWW. While the benefits of using TWW for irrigation are apparent, evidence of its negative effects on soil, trees, and yield is accumulating. This study, performed in a commercial TWW-irrigated citrus orchard in central Israel, examined the effects of (1) soil-wettability decrease due to prolonged TWW irrigation on the spatial and temporal distribution of water content and associated chemical properties in the root zone; (2) the conversion of irrigation in half of the TWW-irrigated research plot to FW (2012) for soil reclamation. Electrical resistivity tomography surveys in the substantially water repellent soils revealed that water flow is occurring along preferential flow paths in both plots, leaving behind a considerably nonuniform water-content distribution. This was despite the gradual relief in soil water repellency measured in the FW plots. Four soil-sampling campaigns (spring and fall, 2014-2016), performed in 0-20 and 20-40 cm layers of the research plot, revealed bimodal gravimetrically measured water-content distribution. The preferential flow led to uneven chemical-property distribution, with substantially high concentrations in the dry spots, and lower concentrations in the wet spots along the preferential flow paths. The average salt and nutrient concentrations, which were initially high in both plots, gradually dispersed with time, as concentrations in the FW plots decreased. Nevertheless, the efficiency of reclaiming TWW soil by FW irrigation appears low.

  4. Risk Assessment of Hurricane Storm Surge for Tampa Bay

    Science.gov (United States)

    Lin, N.; Emanuel, K.

    2011-12-01

    Hurricane storm surge presents a major hazard for the United States and many other coastal areas around the world. Risk assessment of current and future hurricane storm surge provides the basis for risk mitigation and related decision making. This study investigates the hurricane surge risk for Tampa Bay, located on the central west coast of Florida. Although fewer storms have made landfall in the central west Florida than in regions farther west in the Gulf of Mexico and the east coast of U.S., Tampa Bay is highly vulnerable to storm surge due to its geophysical features. It is surrounded by low-lying lands, much of which may be inundated by a storm tide of 6 m. Also, edge waves trapped on the west Florida shelf can propagate along the coastline and affect the sea level outside the area of a forced storm surge; Tampa Bay may be affected by storms traversing some distance outside the Bay. Moreover, when the propagation speed of the edge wave is close to that of a storm moving parallel to the coast, resonance may occur and the water elevation in the Bay may be greatly enhanced. Therefore, Tampa Bay is vulnerable to storms with a broad spectrum of characteristics. We apply a model-based risk assessment method to carry out the investigation. To estimate the current surge risk, we apply a statistical/deterministic hurricane model to generate a set of 1500 storms for the Tampa area, under the observed current climate (represented by 1981-2000 statistics) estimated from the NCAR/NCEP reanalysis. To study the effect of climate change, we use four climate models, CNRM-CM3, ECHAM, GFDL-CM2.0, and MIROC3.2, respectively, to drive the hurricane model to generate four sets of 1500 Tampa storms under current climate conditions (represented by 1981-2000 statistics) and another four under future climate conditions of the IPCC-AR4 A1B emission scenario (represented by 2081-2100 statistics). Then, we apply two hydrodynamic models, the Advanced Circulation (ADCIRC) model and the Sea

  5. Application of computer-assisted mapping to volcanic hazard evaluation of surge eruptions: Vulcano, lipari, and vesuvius

    Science.gov (United States)

    Sheridan, Michael F.; Malin, Michael C.

    1983-09-01

    A previously developed computer-assisted model has been applied to several pyroclastic-surge eruptions at three active volcanoes in Italy. Model hazard maps created for various vent locations, eruption types, and mass production rates reasonably reproduced pyroclastic-surge deposits from several recent eruptions on Vulcano, Lipari, and Vesuvius. Small-scale phreatic eruptions on the island of Vulcano (e.g. the 1727 explosion of Forgia Vecchia) pose a limited but serious threat to the village of Porto. The most dangerous zone affected by this type of eruption follows a NNW fissure system between Fossa and Vulcanello. Moderate-sized eruptions on Vulcano, such as those associated with the present Fossa Crater are a much more serious threat to Porto as well as the entire area within the caldera surrounding the cone. The less frequent surge eruptions on Lipari have been even more violent. The extreme mobility of surges like those produced from Monte Guardia (approx. 20,000 y.b.p.) and Monte Pilato would not only threaten the entire island of Lipari, but also the northern part of neighboring Vulcano. Eruptions at Vesuvius with energy and efficiency similar to that of the May 18, 1980 blast of Mount St. Helens would be still more destructive because of the great initial elevation of the summit vent. In addition, surge eruptions at Vesuvius are generally part of more complex eruption cycles that involve several other types of volcanic phenomena including Plinian fall and pyroclastic flows.

  6. A numerical study of vegetation impact on reducing storm surge by wetlands in a semi-enclosed estuary

    Science.gov (United States)

    Kelin, Hu; Qin, Chen; Wang, Hongqing

    2014-01-01

    Coastal wetlands play a unique role in extreme hurricane events. The impact of wetlands on storm surge depends on multiple factors including vegetation, landscape, and storm characteristics. The Delft3D model, in which vegetation effects on flow and turbulence are explicitly incorporated, was applied to the semi-enclosed Breton Sound (BS) estuary in coastal Louisiana to investigate the wetland impact. Guided by extensive field observations, a series of numerical experiments were conducted based on variations of actual vegetation properties and storm parameters from Hurricane Isaac in 2012. Both the vegetation-induced maximum surge reduction (MSR) and maximum surge reduction rate (MSRR) increased with stem height and stem density, and were more sensitive to stem height. The MSR and MSRR decreased significantly with increasing wind intensity. The MSRR was the highest with a fast-moving weak storm. It was also found that the MSRR varied proportionally to the expression involving the maximum bulk velocity and surge over the area of interest, and was more dependent on the maximum bulk surge. Both MSR and MSRR appeared to increase when the area of interest decreased from the whole BS estuary to the upper estuary. Within the range of the numerical experiments, the maximum simulated MSR and MSRR over the upper estuary were 0.7 m and 37%, respectively.

  7. A surge of the glaciers Skobreen–Paulabreen, Svalbard, observed by time-lapse photographs and remote sensing data

    Directory of Open Access Journals (Sweden)

    Lene Kristensen

    2012-11-01

    Full Text Available We present observations of a surge of the glaciers Skobreen–Paulabreen, Svalbard, during 2003–05, including a time-lapse movie of the frontal advance during 2005, Advanced Spaceborne Thermal Emission (ASTER imagery and oblique aerial photographs. The surge initiated in Skobreen, and then propagated downglacier into the lower parts of Paulabreen. ASTER satellite images from different stages of the surge are used to evaluate the surge progression. Features on the glacier surface advanced 2800 m over 2.4 yr, averaging 3.2 m/day, while the front advanced less (ca. 1300 m due to contemporaneous calving. The surge resulted in a lateral displacement of the medial moraines of Paulabreen of ca. 600 m at the glacier front. The time-lapse movie captured the advance of the frontal part of the glacier, and dramatically illustrates glacier dynamic processes in an accessible way. The movie documents a range of processes such as a plug-like flow of the glacier, proglacial thrusting, incorporation of old, dead ice at the margin, and calving into the fjord. The movie provides a useful resource for researchers, educators seeking to teach and inspire students, and those wishing to communicate the fascination of glacier science to a wider public.

  8. Sediment transport in irrigation canals

    OpenAIRE

    Méndez V., N.J.

    1998-01-01

    The world population is rapidly increasing and is expected to double to about 10 billion by the year 2050. To support an increasing population in terms of food sufficiency, more and more water will be required. Irrigation is the most critical component of the modern package of inputs to effect high crop production. Irrigation has been the largest recipient of public agricultural investment in the developing world. Hence, continued investment in irrigation along with reforms in institutional a...

  9. Evolution of surge levels inside of the Seine Bay : interactions between tide and surge levels during Johanna and Xynthia storms

    Science.gov (United States)

    Laborie, Vanessya; Sergent, Philippe

    2015-04-01

    Within the Technical Commission for the Study and the Evaluation of Maritime Submersions in the Seine Estuary (CTeeSMES), which aim is to improve the collective knowledge on physical processes related to maritime surge levels, a numerical model of the Atlantic French Coast based on TELEMAC2D was used to study the evolution of surge levels from the ocean to the harbour area of Le Havre and evaluate the interactions between tide and surge levels in the Seine Bay. The numerical model was specifically calibrated on JOHANNA and XYNTHIA storm events, which respectively occurred in March 2008 and in February 2010. To calibrate the global signal (tide + surge levels), measurements available on 18 outputs of the Atlantic coast were used to optimize the coefficient for wind influence and for bottom friction. Maritime boundary conditions were provided by the North East Atlantic Atlas (LEGOS). Winds and pressure fields were CFSR data. Once the numerical model had been calibrated both for tide and surge levels, it has been possible to draw the evolution of surge levels from the ocean to Le Havre (quai Meunier) and then to compare the signal obtained at each point of the Seine Bay with that obtained without taking into consideration tide for each event. That also allowed to evaluate the contribution of interactions between tide and surge levels inside of the Seine Bay for Xynthia and Johanna events, but also for other events in the slice [1979-2010] and considering climate change towards 2100 with IPCC5 scenarios. It appears that instantaneous interactions between tide and surge levels nearly reach 50 % of the global surge levels and can sharply influence the evolution of surge levels in the Seine Bay depending of the moment (high tide or low water) at which the storm occurs.

  10. Design of a pot experiment to study the effect of irrigation with ...

    African Journals Online (AJOL)

    and irrigation infrastructure enabled irrigation of more than one soil with diluted winery wastewater in one experiment. It .... A piece of 1.5 mm plastic fly-mesh was placed ... where t is the time (min) and Qdrip is the total flow rate through the four ...

  11. Understanding water delivery performance in a large-scale irrigation system in Peru

    NARCIS (Netherlands)

    Vos, J.M.C.

    2005-01-01

    During a two-year field study the performance of the water delivery was evaluated in a large-scale irrigation system on the north coast of Peru. Flow measurements were carried out along the main canals, along two secondary canals, and in two tertiary blocks in the Chancay-Lambayeque irrigation

  12. The dynamics of surges in the 3 February 2015 avalanches in Vallée de la Sionne

    Science.gov (United States)

    Köhler, A.; McElwaine, J. N.; Sovilla, B.; Ash, M.; Brennan, P.

    2016-11-01

    Five avalanches were artificially released at the Vallée de la Sionne test site in the west of Switzerland on 3 February 2015 and recorded by the GEOphysical flow dynamics using pulsed Doppler radAR Mark 3 radar system. The radar beam penetrates the dilute powder cloud and measures reflections from the underlying denser avalanche features allowing the tracking of the flow at 111 Hz with 0.75 m downslope resolution. The data show that the avalanches contain many internal surges. The large or "major" surges originate from the secondary release of slabs. These slabs can each contain more mass than the initial release, and thus can greatly affect the flow dynamics, by unevenly distributing the mass. The small or "minor" surges appear to be a roll wave-like instability, and these can greatly influence the front dynamics as they can repeatedly overtake the leading edge. We analyzed the friction acting on the fronts of minor surges using a Voellmy-like, simple one-dimensional model with frictional resistance and velocity-squared drag. This model fits the data of the overall velocity, but it cannot capture the dynamics and especially the slowing of the minor surges, which requires dramatically varying effective friction. Our findings suggest that current avalanche models based on Voellmy-like friction laws do not accurately describe the physics of the intermittent frontal region of large mixed avalanches. We suggest that these data can only be explained by changes in the snow surface, such as the entrainment of the upper snow layers and the smoothing by earlier flow fronts.

  13. Application of wind energy to Great Plains irrigation pumping. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hagen, L.J.; Lyles, L.; Skidmore, E.L.

    1979-10-01

    Wind energy systems without energy storage for irrigation in the Great Plains are studied. Major uses of irrigation energy were identified as pumping for surface distribution systems, which could be supplied by variable flow, and pumping for sprinkler systems using constant flow. A computer program was developed to simulate operation of wind-powered irrigation wells. Pumping by wind turbine systems was simulated for 2 variable and 2 constant flow operational modes in which auxiliary motors were used in 3 of the modes. Using the simulation program, the well yields and maximum pumping rates among the 4 modes as a function of drawdown in a typical well are compared.

  14. Comparison of water distribution mechanisms under two localized irrigation techniques (Drip Irrigation & Buried Diffuser) for one week irrigation period in a sandy soil of southeastern Tunisia

    Science.gov (United States)

    Gasmi, Ines; Kodešová, Radka; Mechergui, Mohamed; Nikodem, Antonín; Moussa, Mohamed

    2017-04-01

    The majority of agricultural ecosystems in the Mediterranean basin of northern Africa suffer from water shortage and positions these regions in a highly vulnerable to climate change. In arid regions of Tunisia and exactly in the Southeastern part, during each growing season, plant productivity in sandy-loamy soils is dramatically reduced by limited availability of soil water and nutrients. Thus, highly permeable soils are unable to retain adequate water and nutrient resource in the plant root zone. Moreover, the investments of supplemental irrigation and agricultural amendments of additional fertilization are not sustainable due to the leaching of water supplies and nutrients, which severely limit agricultural productivity. In addition, inadequate soil water distribution, costly irrigation and fertilization leads to negative responses to plant nutrients added to highly permeable soils. That's why we should use irrigation techniques with high water use efficiency. This paper focuses on the comparison between two localized irrigation techniques which are the Drip Irrigation (DI) and the Buried Diffuser (BD) that has the same flow rates (4 l/h). The BD is buried at 15 cm depths. Experimental data was obtained from Smar-Médenine located in South-East of Tunisia. The water distribution at the soil surface for BD is very important about 195 cm2 while for the DI is about 25.12 cm2. The HYDRUS 2D/3D model helped to evaluate the water distribution and compare the water balance obtained with those two irrigation techniques for one week irrigation period. There is a rapid kinetic which has a duration of 3 hours (irrigation time) and a slow kinetic which is the result of the water distribution in the soil, the plant uptake and the effect of climatic condition. There are two mechanisms that affect the two irrigation techniques: the water distribution and the position of irrigation system. As a result, irrigation with BD goes dipper in the soil. The transmission zone for this

  15. Roles of the combined irrigation, drainage, and storage of the canal network in improving water reuse in the irrigation districts along the lower Yellow River, China

    Science.gov (United States)

    Liu, Lei; Luo, Yi; He, Chansheng; Lai, Jianbin; Li, Xiubin

    2010-09-01

    SummaryThe commonly used irrigation system in the irrigation districts (with a combined irrigation area of 3.334 × 10 6 ha) along the lower Yellow River of China is canal network. It delivers water from the Yellow River to the fields, collects surface runoff and drainage from cropland, and stores both of them for subsequent irrigation uses. This paper developed a new combined irrigation, drainage, and storage (CIDS) module for the SWAT2000 model, simulated the multiple roles of the CIDS canal system, and estimated its performance in improving water reuse in the irrigation districts under different irrigation and water diversion scenarios. The simulation results show that the annual evapotranspiration (ET) of the double-cropping winter wheat and summer maize was the highest under the full irrigation scenario (automatic irrigation), and the lowest under the no irrigation scenario. It varied between these two values when different irrigation schedules were adopted. Precipitation could only meet the water requirement of the double-cropping system by 62-96% on an annual basis; that of the winter wheat by 32-36%, summer maize by 92-123%, and cotton by 87-98% on a seasonal basis. Hence, effective irrigation management for winter wheat is critical to ensure high wheat yield in the study area. Runoff generation was closely related to precipitation and influenced by irrigation. The highest and lowest annual runoff accounted for 19% and 11% of the annual precipitation under the full irrigation and no irrigation scenarios, respectively. Nearly 70% of the annual runoff occurred during months of July and August due to the concentrated precipitation in these 2 months. The CIDS canals play an important role in delivering the diversion water from the Yellow River, intercepting the surface runoff and drainage from cropland (inflow of the CIDS canal) and recharging the shallow aquifer for later use. Roughly 14-26% of the simulated total flow in the CIDS canal system recharged

  16. Irrigation trends in Kansas, 1991–2011

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This fact sheet examines trends in total reported irrigation water use and acres irrigated as well as irrigation water use by crop type and system type in Kansas for...

  17. Surge of the Bivachny Glacier in 2012–2015

    Directory of Open Access Journals (Sweden)

    V. M. Kotlyakov

    2015-01-01

    Full Text Available The surge of the Bivachny Glacier that occurred in 2012–2015 is analyzed with the use of photographing performed from International Space Station in 2001–2015 together with data of the satellite monitoring of 1972–2000. This surge happened in 31 years after the similar previous event of 1972–1976. Dynamics of numerous glacier branches causing activation of the lower glacier part that is so called “dead” zone (more than 7 km in length is shown. Just before its stop the front part of the surging glacier had reached the main trunk of the Fedchenko Glacier. 

  18. Soil Water Distribution and Irrigation Uniformity Under Alternative Furrow Irrigation

    Institute of Scientific and Technical Information of China (English)

    PAN Ying-hua; KANG Shao-zhong; DU Tai-sheng; YANG Xiu-ying

    2003-01-01

    Field experiments were conducted to investigate the spatial-temporal distribution and the uni-formity of soil water under alternative furrow irrigation in spring maize field in Gansu Province. Resultsshowed that during the crop growing season, alternative drying and wetting furrows could incur crops to en-dure a water stress, thus the adsorptive ability of root system could be enhanced. As there was no zero fluxplane between irrigated furrows and non-irrigated furrows under alternative furrow irrigation, lateral infiltra-tion of water was obviously increased, thus decreasing the deep percolation. Compared with the conventionalirrigation, although the water consumption in alternative furrow irrigation was reduced, the uniformity of soilwater was not obviously affected.

  19. The comparison between two irrigation regimens on the dentine wettability for an epoxy resin based sealer by measuring its contact angle formed to the irrigated dentine

    Science.gov (United States)

    Mohan, Rayapudi Phani; Pai, Annappa Raghavendra Vivekananda

    2015-01-01

    Aim: The aim was to assess the influence of two irrigation regimens having ethylenediaminetetraacetic acid (EDTA) and ethylenediaminetetraacetic acid with cetrimide (EDTAC) as final irrigants, respectively, on the dentine wettability for AH Plus sealer by comparing its contact angle formed to the irrigated dentine. Materials and Methods: Study samples were divided into two groups (n = 10). The groups were irrigated with 3% sodium hypochlorite (NaOCl) solution followed by either 17% EDTA or 17% EDTAC solution. AH Plus was mixed, and controlled volume droplet (0.1 mL) of the sealer was placed on the dried samples. The contact angle was measured using a Dynamic Contact Angle Analyzer and results were analyzed using SPSS 21.0 and 2 sample t-test. Results: There was a significant difference in the contact angle of AH Plus formed to the dentine irrigated with the above two regimens. AH Plus showed significantly lower contact angle with the regimen having EDTAC as a final irrigant than the one with EDTA (P < 0.05). Conclusion: An irrigation regimen consisting of NaOCl with either EDTA or EDTAC solution as a final irrigant influences the dentine wettability and contact angle of a sealer. EDTAC as a final irrigant facilitates better dentin wettability than EDTA for AH Plus to promote its better flow and adhesion. PMID:26180409

  20. Assessing environmental impacts of constructed wetland effluents for vegetable crop irrigation.

    Science.gov (United States)

    Castorina, A; Consoli, S; Barbagallo, S; Branca, F; Farag, A; Licciardello, F; Cirelli, G L

    2016-01-01

    The objective of this study was to monitor and assess environmental impacts of reclaimed wastewater (RW), used for irrigation of vegetable crops, on soil, crop quality and irrigation equipment. During 2013, effluents of a horizontal sub-surface flow constructed treatment wetland (TW) system, used for tertiary treatment of sanitary wastewater from a small rural municipality located in Eastern Sicily (Italy), were reused by micro-irrigation techniques to irrigate vegetable crops. Monitoring programs, based on in situ and laboratory analyses were performed for assessing possible adverse effects on water-soil-plant systems caused by reclaimed wastewater reuse. In particular, experimental results evidenced that Escherichia coli content found in RW would not present a risk for rotavirus infection following WHO (2006) standards. Irrigated soil was characterized by a certain persistence of microbial contamination and among the studied vegetable crops, lettuce responds better, than zucchini and eggplants, to the irrigation with low quality water, evidencing a bettering of nutraceutical properties and production parameters.

  1. Mud aprons in front of Svalbard surge moraines: Evidence of subglacial deforming layers or proglacial glaciotectonics?

    Science.gov (United States)

    Kristensen, Lene; Benn, Douglas I.; Hormes, Anne; Ottesen, Dag

    2009-10-01

    Large debris-flow units commonly occur on the distal sides of subaqueous end moraines deposited by surges of Svalbard tidewater glaciers, but have rarely been described in terrestrial settings. Some researchers have argued that these kinds of debris flows reflect processes unique to the subaqueous environment, such as the extrusion of subglacial deforming layers or extensive failure of oversteepened moraine fronts. In this paper, we describe terrestrial and subaqueous parts of a single late Holocene moraine system deposited by a major surge of the tidewater glacier Paulabreen in west Spitsbergen. The ice-marginal landforms on land closely resemble the corresponding landforms on the seabed as evidenced by geomorphic mapping and geophysical profiles from both environments. Both onland and offshore, extensive areas of hummocky moraine occur on the proximal side of the maximum glacier position, and large mud aprons (interpreted as debris flows) occur on the distal side. We show that the debris-flow sediments were pushed in front of the advancing glacier as a continuously failing, mobile push moraine. We propose that the mud aprons are end members of a proglacial landforms continuum that has thrust-block moraines as the opposite end member. Two clusters of dates (~ 8000 YBP and ~ 700 YBP) have previously been interpreted to indicate two separate surges responsible for the moraine formation. New dates suggest that the early cluster indicates a local extinction of the abounded species Chlamys islandica. Other changes corresponding to the widespread 8.2 ka event within the fjord, may suggest that the extinction of the C. islandica corresponds to that time.

  2. Reuse of reclaimed wastewater for golf course irrigation in Tunisia.

    Science.gov (United States)

    Bahri, A; Basset, C; Oueslati, F; Brissaud, F

    2001-01-01

    In Tunisia, golf courses are irrigated with secondary treated effluent stored in landscape impoundments. The impact of the conveyance and storage steps on the physical-chemical and biological quality of irrigation water was evaluated on three golf courses over two years. It was found that the water quality varies all along the water route, from the wastewater treatment plant up to the irrigation site: nutrient and bacteria contents decreased along the route in the three cases. This variation depends on the wastewater quality, the length of the pipes conveying water, the number of regulation reservoirs and ponds, the water residence time in pipes, reservoirs and ponds, and the operation of the ponds. The bacteriological quality of irrigation water deteriorates during the irrigation period in the three golf courses as the ponds are operated as continuous flow reactors. The results obtained in this study indicate the inability of golf water supplies, as currently managed, to properly sanitize reclaimed wastewater and meet target quality criteria recommended by WHO (1989) for water intended for recreational use. For a safe reuse of reclaimed wastewater for golf course irrigation, changes in the design and operation of the ponds should be planned or additional treatment steps provided.

  3. Irrigation management in organic greenhouse

    NARCIS (Netherlands)

    Voogt, W.; Balendonck, J.; Berkelmans, R.; Enthoven, N.

    2017-01-01

    Irrigation in protected cultivation is essential due to the absence of natural precipitation. High evapotranspiration, due to higher temperature and prolonged cropping period, requires ample an adequate supply of water. The water supply in a greenhouse is solely carried out by irrigation and thus

  4. CROP UNDER DEFICIT IRRIGATION SCHEDULING

    African Journals Online (AJOL)

    This study presents crop coefficient (Kc) values of TMV 1 -ST maize variety ... given time from planting to the time it is harvested. ... real time irrigation scheduling for high frequent and non-fiequent water .... 10 m, and the average soil bulk density was 1420 kg/m'. ...... Performance Evaluation of Fadama Irrigation Practice.

  5. Control of Surge in Centrifugal Compressor by Using a Nozzle Injection System: Universality in Optimal Position of Injection Nozzle

    Directory of Open Access Journals (Sweden)

    Toshiyuki Hirano

    2012-01-01

    Full Text Available The passive control method for surge and rotating stall in centrifugal compressors by using a nozzle injection system was proposed to extend the stable operating range to the low flow rate. A part of the flow at the scroll outlet of a compressor was recirculated to an injection nozzle installed on the inner wall of the suction pipe of the compressor through the bypass pipe and injected to the impeller inlet. Two types of compressors were tested at the rotational speeds of 50,000 rpm and 60,000 rpm with the parameter of the circumferential position of the injection nozzle. The present experimental results revealed that the optimum circumferential position, which most effectively reduced the flow rate for the surge inception, existed at the opposite side of the tongue of the scroll against the rotational axis and did not depend on the compressor system and the rotational speeds.

  6. Centrifugal compressor surge detecting method based on wavelet analysis of unsteady pressure fluctuations in typical stages

    Science.gov (United States)

    Izmaylov, R.; Lebedev, A.

    2015-08-01

    Centrifugal compressors are complex energy equipment. Automotive control and protection system should meet the requirements: of operation reliability and durability. In turbocompressors there are at least two dangerous areas: surge and rotating stall. Antisurge protecting systems usually use parametric or feature methods. As a rule industrial system are parametric. The main disadvantages of anti-surge parametric systems are difficulties in mass flow measurements in natural gas pipeline compressor. The principal idea of feature method is based on the experimental fact: as a rule just before the onset of surge rotating or precursor stall established in compressor. In this case the problem consists in detecting of unsteady pressure or velocity fluctuations characteristic signals. Wavelet analysis is the best method for detecting onset of rotating stall in spite of high level of spurious signals (rotating wakes, turbulence, etc.). This method is compatible with state of the art DSP systems of industrial control. Examples of wavelet analysis application for detecting onset of rotating stall in typical stages centrifugal compressor are presented. Experimental investigations include unsteady pressure measurement and sophisticated data acquisition system. Wavelet transforms used biorthogonal wavelets in Mathlab systems.

  7. U.S. Glaucoma Cases Expected to Surge by 2030

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_162924.html U.S. Glaucoma Cases Expected to Surge by 2030 Routine ... Medicine, the National Institutes of Health, or the U.S. Department of Health and Human Services. Recent Health ...

  8. Zika-Linked Birth Defects Surge in Colombia: CDC

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_162464.html Zika-Linked Birth Defects Surge in Colombia: CDC Study ... born with devastating birth defects linked to the Zika virus is no longer confined to Brazil, a ...

  9. Storm surge model based on variational data assimilation method

    Institute of Scientific and Technical Information of China (English)

    Shi-li HUANG; Jian XU; De-guan WANG; Dong-yan LU

    2010-01-01

    By combining computation and observation information,the variational data assimilation method has the ability to eliminate errors caused by the uncertainty of parameters in practical forecasting.It was applied to a storm surge model based on unstructured grids with high spatial resolution meant for improving the forecasting accuracy of the storm surge.By controlling the wind stress drag coefficient,the variation-based model was developed and validated through data assimilation tests in an actual storm surge induced by a typhoon.In the data assimilation tests,the model accurately identified the wind stress drag coefficient and obtained results close to the true state.Then,the actual storm surge induced by Typhoon 0515 was forecast by the developed model,and the results demonstrate its efficiency in practical application.

  10. Observations of cyclone-induced storm surge in coastal Bangladesh

    OpenAIRE

    Chiu, Soyee; Small, Christopher

    2015-01-01

    Water level measurements from 15 tide gauges in the coastal zone of Bangladesh are analyzed in conjunction with cyclone tracks and wind speed data for 54 cyclones between 1977 and 2010. Storm surge magnitude is inferred from residual water levels computed by subtracting modeled astronomical tides from observed water levels at each station. Observed residual water levels are generally smaller than reported storm surge levels for cyclones where both are available, and many cyclones produce no o...

  11. Phosphorus losses in furrow irrigation runoff.

    Science.gov (United States)

    Westermann, D T; Bjorneberg, D L; Aase, J K; Robbins, C W

    2001-01-01

    Phosphorus (P) often limits the eutrophication of streams, rivers, and lakes receiving surface runoff. We evaluated the relationships among selected soil P availability indices and runoff P fractions where manure, whey, or commercial fertilizer applications had previously established a range of soil P availabilities on a Portneuf silt loam (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid) surface-irrigated with Snake River water. Water-soluble P, Olsen P (inorganic and organic P), and iron-oxide impregnated paper-extractable P (FeO-Ps) were determined on a 0.03-m soil sample taken from the bottom of each furrow before each irrigation in fall 1998 and spring 1999. Dissolved reactive phosphorus (DRP) in a 0.45-microm filtered runoff sample, and iron-oxide impregnated paper-extractable P (FeO-Pw), total P, and sediment in an unfiltered runoff sample were determined at selected intervals during a 4-h irrigation on 18.3-m field plots. The 1998 and 1999 data sets were combined because there were no significant differences. Flow-weighted average runoff DRP and FeO-Pw concentrations increased linearly as all three soil P test concentrations increased. The average runoff total P concentration was not related to any soil P test but was linearly related to sediment concentration. Stepwise regression selected the independent variables of sediment, soil lime concentration, and soil organic P extracted by the Olsen method as related to average runoff total P concentration. The average runoff total P concentration was 1.08 mg L(-1) at a soil Olsen P concentration of 10 mg kg(-1). Soil erosion control will be necessary to reduce P losses in surface irrigation runoff.

  12. The sensitivity of southeastern United States climate to varying irrigation vigor

    Science.gov (United States)

    Selman, Christopher; Misra, Vasubandhu

    2016-07-01

    Four regional climate model runs centered on the Southeast United States (SEUS) assuming a crop growing season of May through October are irrigated at 25% (IRR25), 50% (IRR50), 75% (IRR75), and 100% (IRR100) of the root zone porosity to assess the sensitivity of the SEUS climate to irrigation. A fifth run, assuming no irrigation (CTL), is used as the basis for comparison. Across all IRR runs, it is found that there is a general reduction in seasonal mean precipitation over the irrigated cells relative to CTL. This manifests as an increase in dry (0-1 mm/d) days and reduction in > 1 mm/d rainfall events. A comparative moisture budget reveals that area-averaged precipitation over the irrigated cells displays a reduction in precipitation and runoff in IRR100 with a weaker reduction in IRR25. This is despite an increase in vertically integrated moisture convergence and local evaporation. We find that irrigation increases the lower atmospheric stability, which in turn reduces the convective rainfall over the irrigated areas. Seasonally averaged temperatures reduce over irrigated areas, with the intensity of the reduction increasing with irrigation vigor. This is largely attributed to a repartitioning of sensible heat flux into latent heat flux. There is also, however, a small increase of heat flow to deeper soil layers. Precipitation ahead of transient cold fronts is also reduced by irrigation as they pass over irrigated cells, owing to the increased stability in the lower troposphere. The intensity of this precipitation reduction becomes more intense as irrigation vigor increases. Lastly, heat waves in the SEUS are reduced in intensity over irrigated cells.

  13. The surge-like eruption of a miniature filament

    Institute of Scientific and Technical Information of China (English)

    Jia-Yan Yang; Yun-Chun Jiang; Dan yang; Yi Bi; Bo Yang; Rui-Sheng Zheng; Jun-Chao Hong

    2012-01-01

    We report on the rare eruption of a miniature Hα filament that took the form of a surge.The filament first underwent a full development within 46 min and then began to erupt 9 min later,followed by a compact,impulsive X-ray class M2.2 flare with a two-ribbon nature only at the early eruption phase.During the eruption,its top rose,whereas the two legs remained rooted in the chromosphere and showed little swelling perpendicular to the rising direction.This led to a surge-like eruption with a narrow angular extent.Similar to the recent observations for standard and blowout X-ray jets by Moore et al.,we thus define it as a "blowout Hα surge." Furthermore,our observations showed that the eruption was associated with (1) a coronal mass ejection guided by a pre-existing streamer,(2) abrupt,significant,and persistent changes in the photospheric magnetic field around the filament,and (3) a sudden disappearance of a small pore.These observations thus provide evidence that a blowout surge is a small-scale version of a large-scale filament eruption in many aspects.Our observations further suggest that at least part of the Hα surges belong to blowout-type cases,and the exact distinction between the standard and blowout Hα surges is important in understanding their different origins and associated eruptive phenomena.

  14. The role of mangroves in attenuating storm surges

    Science.gov (United States)

    Zhang, Keqi; Liu, Huiqing; Li, Yuepeng; Xu, Hongzhou; Shen, Jian; Rhome, Jamie; Smith, J.

    2012-01-01

    Field observations and numerical simulations indicate that the 6-to-30-km-wide mangrove forest along the Gulf Coast of South Florida effectively attenuated stormsurges from a Category 3 hurricane, Wilma, and protected the inland wetland by reducing an inundation area of 1800 km2 and restricting surge inundation inside the mangrove zone. The surge amplitude decreases at a rate of 40–50 cm/km across the mangrove forest and at a rate of 20 cm/km across the areas with a mixture of mangrove islands with open water. In contrast, the amplitudes of stormsurges at the front of the mangrove zone increase by about 10–30% because of the "blockage" of mangroves to surge water, which can cause greater impacts on structures at the front of mangroves than the case without mangroves. The mangrove forest can also protect the wetlands behind the mangrove zone against surge inundation from a Category 5 hurricane with a fast forward speed of 11.2 m/s (25 mph). However, the forest cannot fully attenuate stormsurges from a Category 5 hurricane with a slow forward speed of 2.2 m/s (5 mph) and reduced surges can still affect the wetlands behind the mangrove zone. The effects of widths of mangrove zones on reducing surge amplitudes are nonlinear with large reduction rates (15–30%) for initial width increments and small rates (<5%) for subsequent width increments.

  15. Improved PV system reliability results from surge evaluations at Sandia National Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Russell H. Bonn; Sigifredo Gonzalez

    2000-04-11

    Electrical surges on ac and dc inverter power wiring and diagnostic cables have the potential to shorten the lifetime of power electronics. These surges may be caused by either nearby lightning or capacitor switching transients. This paper contains a description of ongoing surge evaluations of PV power electronics and surge mitigation hardware at Sandia.

  16. Alternating irrigation water quality as a method to control solute concentrations and mass fluxes below irrigated fields: A numerical study

    Science.gov (United States)

    Russo, David

    2016-05-01

    The aim of the present numerical study was to extend the data-driven protocol for the control of soil salinity, to control chloride and nitrate concentrations and mass fluxes below agricultural fields irrigated with treated waste water (TWW). The protocol is based on alternating irrigation water quality between TWW and desalinized water (DSW), guided by solute concentrations at soil depth, zs. Two different schemes, the first requires measurements of soil solution concentrations of chloride and nitrate at zs, while, the second scheme requires only measurements of soil solution EC at zs, were investigated. For this purpose, 3-D numerical simulations of flow and transport were performed for variably saturated, spatially heterogeneous, flow domains located at two different field sites. The sites differ in crop type, irrigation method, and in their lithology; these differences, in turn, considerably affect the performance of the proposed schemes, expressed in terms of their ability to reduce solute concentrations that drained below the root zone. Results of the analyses suggest that the proposed data-driven schemes allow the use of low-quality water for irrigation, while minimizing the consumption of high-quality water to a level, which, for given climate, soil, crop, irrigation method, and water quality, may be determined by the allowable nitrate and chloride concentrations in the groundwater. The results of the present study indicate that with respect to the diminution of groundwater contamination by chloride and nitrate, the more data demanding, first scheme is superior the second scheme.

  17. Surge-type glaciers in the Tien Shan (Central Asia)

    Science.gov (United States)

    Mukherjee, Kriti; Bolch, Tobias

    2016-04-01

    Surge-type glaciers in High Mountain Asia are mostly observed in Karakoram and Pamir. However, few surge-type glaciers also exist in the Tien Shan, but have not comprehensively studied in detail in the recent literature. We identified surge-type glaciers in the Tien Shan either from available literature or by manual interpretation using available satellite images (such as Corona, Hexagon, Landsat, SPOT, IRS) for the period 1960 to 2014. We identified 39 possible surge-type glaciers, showing typical characteristics like looped moraines. Twenty-two of them rapidly advanced during different periods or a surge was clearly described in the literature. For the remaining possible surge-type glaciers either the advance, in terms of time and length, were not mentioned in detail in the literature, or the glaciers have remained either stable or retreated during the entire period of our study. Most of the surge-type glaciers cluster in the Inner Tien Shan (especially in the Ak-Shiirak rage) and the Central Tien Shan, are in size and are facing North, West or North West. Pronounced surge events were observed for North Inylchek and Samoilowitsch glaciers, both of which are located in the Central Tien Shan. Samoilowitsch Glacier retreated by more than 3 km between 1960 (length ~8.9 km) and 1992 (~5.8 km), advanced by almost 3 km until 2006 and slightly retreated thereafter. The most pronounced advance occurred between 2000 and 2002. DEM differencing (based on SRTM3 data and stereo Hexagon and Cartosat-1 data) revealed a significant thickening in the middle reaches (reservoir area) of the glacier between 1973 and 2000 while the surface significantly lowered in the middle and upper parts of the glacier between 2000 and 2006. Hence, the ice mass was transferred to the lower reaches (receiving area) and caused the advance with a maximum thickening of more than 80 m. The ~30 km long North Inylchek Glacier retreated since 1943 and showed a very rapid advance of ~3.5 km especially in

  18. CFD Analysis of the Anti-Surge Effects by Water Hammering

    Science.gov (United States)

    Kim, Tae-oh; Jeong, Hyo-min; Chung, Han-shik; Lee, Sin-il; Lee, Kwang-sung

    2015-09-01

    Water hammering occurs due to the surge effect that comes from operating the pump, sudden stop during the operating due to a blackout and rapid open and close of the valve. By the water hammering of the pipeline and the pump, the valve are damaged. In this paper, transient analysis is conducted by CFD (Computational Fluid Dynamics). The purpose of this paper is to provide the research data about the change of the pressure and flow in the pipe that caused by the water hammering.

  19. Experimental and Numerical Investigations of Surge Extension on a Centrifugal Compressor with Vaned Diffuser Using Steam Injection

    Directory of Open Access Journals (Sweden)

    Chuang Gao

    2017-01-01

    Full Text Available This paper presents the first report on surge extension with steam injection through both experimental and numerical simulation. The experimental section covers the test facility, instrumentation, and prestall modes comparison with and without steam injection. It is found that surge extension is not in proportion to injected steam. There exists an upper bound above which deteriorates the margin. Injection of less than 1% of the designed mass flow can bring about over 10% margin improvement. Test results also indicated that steam injection not only damps out prestall waves, but also changes prestall modes and traveling direction. At 90% speed, injection changed the prestall mode from spike to modal, while at 80% speed line, it made the forward traveling wave become backward. Through numerical simulation, location and number of injectors, molecular weight, and temperature of injected gas are modified to explore their influences on surge margin. Similar to the test results, there exists an upper bound for the amount of steam injected. The flow field investigation indicates that this bound is caused by the early trigger of flow collapse due to the injected steam which is similar to the tip leakage flow spillage caused spike stall in axial compressors.

  20. Lethal Thermal Impact at Periphery of Pyroclastic Surges: Evidences at Pompeii

    Science.gov (United States)

    Mastrolorenzo, Giuseppe; Petrone, Pierpaolo; Pappalardo, Lucia; Guarino, Fabio M.

    2010-01-01

    Background The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized. Pompeii and the nearby archaeological sites preserve the most complete set of evidence of the 79 AD catastrophic eruption recording its effects on structures and people. Methodology/Principal Findings Here we investigate the causes of mortality in PDCs at Pompeii and surroundings on the bases of a multidisciplinary volcanological and bio-anthropological study. Field and laboratory study of the eruption products and victims merged with numerical simulations and experiments indicate that heat was the main cause of death of people, heretofore supposed to have died by ash suffocation. Our results show that exposure to at least 250°C hot surges at a distance of 10 kilometres from the vent was sufficient to cause instant death, even if people were sheltered within buildings. Despite the fact that impact force and exposure time to dusty gas declined toward PDCs periphery up to the survival conditions, lethal temperatures were maintained up to the PDCs extreme depositional limits. Conclusions/Significance This evidence indicates that the risk in flow marginal zones could be underestimated by simply assuming that very thin distal deposits, resulting from PDCs with poor total particle load, correspond to negligible effects. Therefore our findings are essential for hazard plans development and for actions aimed to risk mitigation at Vesuvius and other explosive volcanoes. PMID:20559555

  1. Lethal thermal impact at periphery of pyroclastic surges: evidences at Pompeii.

    Directory of Open Access Journals (Sweden)

    Giuseppe Mastrolorenzo

    Full Text Available BACKGROUND: The evaluation of mortality of pyroclastic surges and flows (PDCs produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized. Pompeii and the nearby archaeological sites preserve the most complete set of evidence of the 79 AD catastrophic eruption recording its effects on structures and people. METHODOLOGY/PRINCIPAL FINDINGS: Here we investigate the causes of mortality in PDCs at Pompeii and surroundings on the bases of a multidisciplinary volcanological and bio-anthropological study. Field and laboratory study of the eruption products and victims merged with numerical simulations and experiments indicate that heat was the main cause of death of people, heretofore supposed to have died by ash suffocation. Our results show that exposure to at least 250 degrees C hot surges at a distance of 10 kilometres from the vent was sufficient to cause instant death, even if people were sheltered within buildings. Despite the fact that impact force and exposure time to dusty gas declined toward PDCs periphery up to the survival conditions, lethal temperatures were maintained up to the PDCs extreme depositional limits. CONCLUSIONS/SIGNIFICANCE: This evidence indicates that the risk in flow marginal zones could be underestimated by simply assuming that very thin distal deposits, resulting from PDCs with poor total particle load, correspond to negligible effects. Therefore our findings are essential for hazard plans development and for actions aimed to risk mitigation at Vesuvius and other explosive volcanoes.

  2. Lethal thermal impact at periphery of pyroclastic surges: evidences at Pompeii.

    Science.gov (United States)

    Mastrolorenzo, Giuseppe; Petrone, Pierpaolo; Pappalardo, Lucia; Guarino, Fabio M

    2010-06-15

    The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized. Pompeii and the nearby archaeological sites preserve the most complete set of evidence of the 79 AD catastrophic eruption recording its effects on structures and people. Here we investigate the causes of mortality in PDCs at Pompeii and surroundings on the bases of a multidisciplinary volcanological and bio-anthropological study. Field and laboratory study of the eruption products and victims merged with numerical simulations and experiments indicate that heat was the main cause of death of people, heretofore supposed to have died by ash suffocation. Our results show that exposure to at least 250 degrees C hot surges at a distance of 10 kilometres from the vent was sufficient to cause instant death, even if people were sheltered within buildings. Despite the fact that impact force and exposure time to dusty gas declined toward PDCs periphery up to the survival conditions, lethal temperatures were maintained up to the PDCs extreme depositional limits. This evidence indicates that the risk in flow marginal zones could be underestimated by simply assuming that very thin distal deposits, resulting from PDCs with poor total particle load, correspond to negligible effects. Therefore our findings are essential for hazard plans development and for actions aimed to risk mitigation at Vesuvius and other explosive volcanoes.

  3. Sensing technologies for precision irrigation

    CERN Document Server

    Ćulibrk, Dubravko; Minic, Vladan; Alonso Fernandez, Marta; Alvarez Osuna, Javier; Crnojevic, Vladimir

    2014-01-01

    This brief provides an overview of state-of-the-art sensing technologies relevant to the problem of precision irrigation, an emerging field within the domain of precision agriculture. Applications of wireless sensor networks, satellite data and geographic information systems in the domain are covered. This brief presents the basic concepts of the technologies and emphasizes the practical aspects that enable the implementation of intelligent irrigation systems. The authors target a broad audience interested in this theme and organize the content in five chapters, each concerned with a specific technology needed to address the problem of optimal crop irrigation. Professionals and researchers will find the text a thorough survey with practical applications.

  4. Soil management and conservation: Irrigation: Methods

    Science.gov (United States)

    Irrigation applies water to soil to improve crop production. The three main methods of irrigation are surface, sprinkler and micro. Surface irrigation is used on 85% of the irrigated land in the world. It generally requires lower capital investment because the soil conveys water within the field, ra...

  5. Wireless sensor networks for irrigation management

    Science.gov (United States)

    Sustaining an adequate food supply for the world's population will require advancements in irrigation technology and improved irrigation management. Site-specific irrigation and automatic irrigation scheduling are examples of strategies to deal with declining arable land and limited fresh water reso...

  6. 76 FR 20971 - Turlock Irrigation District and Modesto Irrigation District; Notice of Intent To File License...

    Science.gov (United States)

    2011-04-14

    ... Energy Regulatory Commission Turlock Irrigation District and Modesto Irrigation District; Notice of..., 2011. d. Submitted By: Turlock Irrigation District and Modesto Irrigation District. e. Name of Project... Regulatory Affairs, Turlock Irrigation District, P.O. Box 949, Turlock, California 95381, 209-883-8241...

  7. Performances du goutte à goutte enterré pour l’irrigation de jeunes palmiers dattiers

    Directory of Open Access Journals (Sweden)

    R. BOURZIZA

    2017-03-01

    Full Text Available In oasis areas, surface water resources are becoming increasingly scarce. Groundwater resources are often overexploited, and are of poor quality for their high salinity degree. Water conservation and economy have therefore become imperative for better oases durability. If localized irrigation is currently recommended in Morocco for saving water, its use in the sub-desert areas does not keep water safe from high evaporation rates. An alternative to this system would be the use of subsurface drip irrigation. This technique is defined as an application of water under soil surface through drippers, which discharge water at generally similar rates as the surface drip irrigation. As subsurface drip irrigation is a newly introduced technique in Morocco, a better understanding in local conditions of the infiltration process around a buried source, and its impact on plant growth is necessarily required. This study aims to contribute to improving the efficiency of water use by testing the performance of subsurface drip irrigation system, especially in areas where water is a limited resource. The objectives of this research are performance evaluation in arid conditions of the subsurface drip irrigation system for young date palms compared to the surface drip, as well as determining the appropriate method of flow measurement for a buried dripper. In this context, an experimental plot was installed on a farm in the region of Erfoud (Errachidia Province, Southeast Morocco to characterize the respective performances of surface and subsurface drip irrigation on young date palm. Flow measurement to calculate the uniformity of the application of water was done through two methods: a flow measurement of drippers above the surface and another one underground. The latter method has also helped us to estimate losses through evaporation for both irrigation techniques. In addition, in order to compare the effect of two irrigation modes, plants were identified at random

  8. Study of a Novel Oscillating Surge Wave Energy Converter: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-08-01

    This study investigates the performance of an oscillating surge wave energy converter (OSWEC) that utilizes adjustable geometry as a means of controlling the hydrodynamic coefficients, a concept originally proposed by [1]. The body of the device consists of a bottom-hinged solid rectangular frame with five horizontal flaps spanning the interior of the frame. The flaps can rotate independently about their center of rotation within the frame like a large window shutter. Changing the orientation of the flaps alters the hydrodynamic coefficients and natural frequency of the device as well as the ability to shed or absorb structural loads accordingly. This ability may allow the device to operate in a wider range of sea states than other current wave energy converter designs. This paper presents and compares the results of numerical simulations and experimental testing of the OSWEC's response to regular waves with all five of the horizontal fin configurations sharing the same orientation of 0 degrees (fully closed interior) and 90 degrees (fully open). The numerical simulations were performed using WAMIT, which calculates hydrodynamic coefficients using a boundary element method code to solve the linear potential flow problem, and WEC-Sim, a MATLAB-based tool that simulates multibody devices in the time domain by solving the governing equations of motion. A 1:14 scale model of the device was built for experimental evaluation in an 8-m-long, 1-m wide wave tank, which supports a water depth of 0.7 m. The OSWEC motion in different wave conditions was measured with displacement sensors while nonlinear wave-structure interaction effects like slamming and overtopping were captured using a high-speed camera and used to understand differences between the simulation and experiments.

  9. Modified Streamflows 1990 Level of Irrigation : Columbia River and Coastal Basins, 1928-1989.

    Energy Technology Data Exchange (ETDEWEB)

    United States. Bonneville Power Administration; A.G. Crook Company

    1993-04-01

    The annual operation plans described in the following sections require detailed system regulation computer model studies. These system regulation studies are necessary to evaluate potential new projects and to develop operational rule curves for the existing system of projects. The objective is to provide a basis for evaluating alternative system regulation scenarios. This provides essential input for optimizing the management of existing projects and planning future projects for the most beneficial use of the water supply and resources in the entire region. Historical streamflows per se are inadequate for system regulation studies because the pattern of observed flow has continually changed with each successive stage of irrigation and e development. The problem, therefore, is to adjust for past operation of storage projects and to determine the necessary adjustments that should be made to recorded flows to reflect current stages of irrigation development. Historical flows which have been adjusted to a common level of irrigation development by correcting for the effects of diversion demand, return flow, and change-of-contents and evaporation in upstream reservoirs and lakes are referred to as modified flows. This report describes the development of irrigation depletion adjustments and modified flows for the 1990 level of development for the 61-year period 1928--1989. incremental depletion adjustments were computed in this report for each month of the 61-year period to adjust the effects of actual irrigation in each year up to that which would have been experienced with the irrigation as practiced in 1990.

  10. Numerical simulation and flow field analysis of backwashing of quartz sand filter in micro-irrigation%微灌石英砂过滤器反冲洗数值模拟验证与流场分析

    Institute of Scientific and Technical Information of China (English)

    李景海; 翟国亮; 黄修桥; 冯俊杰; 刘杨

    2016-01-01

    Backwashing of quartz sand filter in micro-irrigation is an effective way to realize the regeneration of quartz sand filter media. Analysis of flow field in the backwashing process of quartz sand filter and determination of reasonable backwashing velocity play an important role in the design and operation of the quartz sand filter. The method of numerical simulation has obvious advantage in the analysis and investigation of the flow field in the filter layer. In order to realize the numerical simulation of the backwashing process of quartz sand filter, the geometric model of quartz sand filter was established through Gambit software, and the mesh division of the geometric model was carried out. Because the backwashing process of quartz sand filter layer is a solid-liquid multiphase flow system interacted by both water and quartz sand, in which quartz sand particles are distributed only in a part of the region during the process of backwashing, not being carried away to outside of the filter by the stream, and in which quartz sand accounted for a larger proportion of the whole volume, the Eulerian model was adopted as a model for numerical simulation of backwashing. At the same time, because the backwashing process of quartz sand filter layer is a dynamically stable process, the transient simulation solver was adopted. The simulation objects were three kinds of quartz sand filter layer with the same thickness of 400 mm, but the equivalent particle size were 1.06, 1.2 and 1.5 mm respectively. In order to verify the reliability of simulation results, backwashing experiments were conducted in Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, in 2014. The parameters such as backwashing velocity, pressure drop and expansion height of filter layer were measured. The simulation results were compared with the experimental results. Comparison showed that the maximum simulation error of the whole pressure drop of filter layer was 7.03%, and the

  11. Numerical experiments of dynamical processes during the 2011-2013 surge of the Bering-Bagley Glacier System, using a full-Stokes finite element model

    Science.gov (United States)

    Trantow, Thomas

    The Bering-Bagley Glacial System (BBGS) is the largest glacier system outside of the Greenland and Antarctic ice sheets, and is the Earth's largest surge-type glacier. Surging is one of three types of glacial acceleration and the least understood one. Understanding glacial acceleration is paramount when trying to explain ice discharge to the oceans and the glacial contribution to sea-level rise, yet there are currently no numerical glacial models that account for surging. The recent 2011-2013 surge of the BBGS provides a rare opportunity to study the surge process through observations and the subsequent data analysis and numerical modeling. Using radar, altimeter, and image data collected from airborne and satellite missions, various descriptions of ice geometry are created at different times throughout the surge. Using geostatistical estimation techniques including variography and ordinary kriging, surface and bedrock Digital Elevation Maps (DEMs) are derived. A time series analysis of elevation change during the current surge is then conducted and validated using a complete error analysis along with airborne observations. The derived DEMs are then used as inputs to a computer simulated model of glacier dynamics in the BBGS. Using the Finite Element software Elmer/Ice, a full-Stokes simulation, with Glen's flow law for temperate ice, is created for numerical experiments. With consideration of free surface evolution, glacial hydrology and surface mass balance, the model is able to predict a variety of field variables including velocity, stress, strain-rate, pressure and surface elevation change at any point forward in time. These outputs are compared and validated using observational data such as CryoSat-2 altimetry, airborne field data, imagery and previous detailed analysis of the BBGS. Preliminary results reveal that certain surge phenomena such as surface elevation changes, surge progression and locations at which the surge starts, can be recreated using the

  12. Effects of irrigated agroecosystems: 1. Quantity of soil water and groundwater in the southern High Plains, Texas

    Science.gov (United States)

    Scanlon, B. R.; Reedy, R. C.; Gates, J. B.

    2010-09-01

    Although irrigated agriculture is the primary consumer of global groundwater resources, information on recharge rates and sustainable irrigation is limited. The study objective was to fingerprint irrigation return flow to quantify percolation/recharge and to estimate sustainable irrigation levels. This paper focuses on water quantity; a companion paper addresses water quality. Soil samples from 13 boreholes drilled beneath irrigated agroecosystems in the southern High Plains were analyzed for matric potential and water-extractable Cl and NO3. Unsaturated zone pore water beneath irrigated agroecosystems can be fingerprinted by higher matric potentials (wetter soils, median mp: -40 m) and higher NO3-N (median 71 mg/L) than beneath natural ecosystems (mp -200 m; NO3-N 8.1 mg/L) and by higher Cl (720 mg/L) than beneath rain-fed agroecosystems (8.4 mg/L). The range in percolation/recharge rates beneath irrigated agroecosystems is 18-97 mm/a (median 41 mm/a; 5% of irrigation + precipitation) and occurs primarily in response to extreme precipitation events. Similarity in percolation/recharge rates beneath irrigated and rain-fed (4.8-92 mm/a) agroecosystems was unexpected and is attributed to low irrigation applications (median 300 mm/a) and increased crop yield and evapotranspiration in irrigated areas. Regional water table declines are unsustainably large (≥ 30 m over 10,000 km2) in the north and are much lower in the south. Sustainable irrigation in the south would require reduction of the irrigated area from 23% to 9%. Methods developed for quantifying recharge and sustainable irrigation application rates can be applied to groundwater-fed irrigated areas in semiarid regions globally.

  13. Surge and swab pressures in wells with cross-section changes; Pressoes de surge and swab em pocos com variacao de secao

    Energy Technology Data Exchange (ETDEWEB)

    Fedevjcyk, Joao Victor; Junqueira, Silvio Luiz de Mello; Negrao, Cezar Otaviano Ribeiro [Universidade Tecnologica Federal do Parana (UTFPR). Laboratorio de Ciencias Termicas (Lacit) (Brazil)], e-mails: silvio@utfpr.edu.br, negrao@utfpr.edu.br

    2009-12-15

    Well drilling is performed by rotating and applying a weighted drill bit to the geological formation. Well diameter variations and the use of drill pipe accessories might cause changes to the annular cross section space between the drill pipe and the borehole. It should be noted cross section changes influence pressure losses within the well. This study proposes a mathematical/ numerical model to simulate the surge and swab problem in wells with variable cross section areas. The fluid flow yielded by the drill pipe motion is considered to be one-dimensional, isothermal, compressible and transient. The proposed model features the mass and momentum conservation equations, along with a state equation and a constitutive equation for Bingham or Power Law fluids. The governing equations were discretized by the Finite Volume Method. The well is assumed to be impermeable and the drill pipe end to be closed. The results were compared to measured data obtained at the Taquipe experimental well with good agreement. Predictions can now be made as to how changes in cross section areas may significantly affect the transient surge and swab pressures. (author)

  14. Irrigation Controllers Specification and Certification

    Science.gov (United States)

    WaterSense labeled irrigation controllers, which act like a thermostat for your sprinkler system telling it when to turn on and off, use local weather and landscape conditions to tailor watering schedules to actual conditions on the site.

  15. Assessing the Impact of Topography on Groundwater Salinization Due to Storm Surge Inundation

    Science.gov (United States)

    Yu, X.; Yang, J.; Graf, T.; Koneshloo, M.; O'Neal, M. A.; Michael, H. A.

    2015-12-01

    The sea-level rise and increase in the frequency and intensity of coastal storms due to climate change are likely to exacerbate adverse effects of storm surges on low-lying coastal areas. The landward flow of water during storm surges introduces salt to surficial coastal aquifers and threatens groundwater resources. Coastal topography (e.g. ponds, dunes, canals) likely has a strong impact on overwash and salinization processes, but is generally highly simplified in modeling studies. To understand the topographic impacts on groundwater salinization, we modeled overwash and variable-density groundwater flow and salt transport in 3D using the fully coupled surface and subsurface numerical simulator, HydroGeoSphere. The model simulates the coastal aquifer as an integrated system considering processes such as overland flow, coupled surface and subsurface exchange, variably saturated flow, and variable-density flow. To represent various coastal landscape types, we started with realistic coastal topography from Delaware, USA, and then generated synthetic fields with differing shore-perpendicular connectivity and surface depressions. The groundwater salinization analysis suggested that the topographic connectivity promoting overland flow controls the volume of aquifer that is salinized. In contrast, depression storage of surface water mainly controls the time for infiltrated salt to flush from the aquifer. The results indicate that for a range of synthetic conditions, topography increases the flushing time of salt by 20-300% relative to an equivalent "simple slope" in which topographic variation is absent. Our study suggests that topography have a significant impact on overwash salinization, with important implications for land management at local scales and groundwater vulnerability assessment at regional to global scales.

  16. New technologies for modernization and management of irrigation piping

    Directory of Open Access Journals (Sweden)

    Alessandro Santini

    2006-07-01

    Full Text Available Improving the efficiency of irrigation piping-systems represents a fundamental prerequisite to achieve a sustainable irrigation under both the environmental the economic point of view. Such an issue is important not only in areas with limited water-budget, but even in those areas where the increasing reduction of the water availability has become a worrying perspective. In the last twenty years, the reduction in water-availability and the increasing costs of system-management have highly limited the cultivated areas which are irrigated by means of water-distribution nets. In the recent years, most of the Italian investments in the irrigation-field have been oriented toward upgrading the open-channels irrigation nets, which were built starting from 50’, by substituting these latter with pipes. The modernization of the piping-systems has been achieved via innovative design solutions, such as back and loading water tanks or towers, which have lead to an improvement into the flexibility of the net management. Nearby the employment of such technologies, nowadays it is also possible to use the knowledge of the physical processes involved in the management of an irrigation system, starting from energy as well as mass exchange in the continuum soil-plant-atmosphere till to a detailed hydraulic description of a water distribution net under different flow regimes. Such a type of knowledge may be used to improve as well as buildup mathematical models for a decisions-support toward the management of complex irrigation districts. The acquirement of the data needed to implement such models has been deeply improved thanks to Geographical Information Systems (GIS, and techniques to analyze satellite-data coming from the Earth observation, which enable to characterize and monitor vegetation at different spatial, spectral and radiometric resolutions.

  17. Cold surge: a sudden and spatially varying threat to health?

    Science.gov (United States)

    Yang, Tse-Chuan; Wu, Pei-Chih; Chen, Vivian Yi-Ju; Su, Huey-Jen

    2009-05-01

    While cold surge is one of the most conspicuous features of the winter monsoon in East Asia, its impact on human health remains underexplored. Based on the definition by the Central Weather Bureau in Taiwan, we identified four cold surges between 2000 and 2003 and collected the cardiovascular disease mortality data 2 weeks before and 2 weeks after these events. We attempted to answer the following research questions: 1) whether the cold surges impose an adverse and immediate effect on cardiovascular mortality; 2) whether the people living in temperate zones have a higher tolerance of extreme temperature drop than those in the subtropics. With geographic weighting techniques, we not only found that the cardiovascular disease mortality rates increased significantly after the cold surges, but also discovered a spatially varying pattern of tolerance to cold surges. Even within a small study area such as Taiwan, human reaction to severe weather drop differs across space. Needless to say, in the U.S., these findings should be considered in redirecting policy to address populations living in warm places when extreme temperature drops occur.

  18. Inputs of nutrients and fecal bacteria to freshwaters from irrigated agriculture: case studies in Australia and New Zealand.

    Science.gov (United States)

    Wilcock, Robert J; Nash, David; Schmidt, Jochen; Larned, Scott T; Rivers, Mark R; Feehan, Pat

    2011-07-01

    Increasing demand for global food production is leading to greater use of irrigation to supplement rainfall and enable more intensive use of land. Minimizing adverse impacts of this intensification on surface water and groundwater resources is of critical importance for the achievement of sustainable land use. In this paper we examine the linkages between irrigation runoff and resulting changes in quality of receiving surface waters and groundwaters in Australia and New Zealand. Case studies are used to illustrate impacts under different irrigation techniques (notably flood and sprinkler systems) and land uses, particularly where irrigation has led to intensification of land use. For flood irrigation, changes in surface water contaminant concentrations are directly influenced by the amount of runoff, and the intensity and kind of land use. Mitigation for flood irrigation is best achieved by optimizing irrigation efficiency. For sprinkler irrigation, leaching to groundwater is the main transport path for contaminants, notably nitrate. Mitigation measures for sprinkler irrigation should take into account irrigation efficiency and the proximity of intensive land uses to sensitive waters. Relating contaminant concentrations in receiving groundwaters to their dominant causes is often complicated by uncertainty about the subsurface flow paths and the possible pollutant sources, viz. drainage from irrigated land. This highlights the need for identification of the patterns and dynamics of surface and subsurface waters to identify such sources of contaminants and minimize their impacts on the receiving environments.

  19. IN VITRO COMPARISON OF MAXIMUM PRESSURE DEVELOPED BY IRRIGATION SYSTEMS IN A KIDNEY MODEL.

    Science.gov (United States)

    Proietti, Silvia; Dragos, Laurian; Somani, Bhaskar K; Butticè, Salvatore; Talso, Michele; Emiliani, Esteban; Baghdadi, Mohammed; Giusti, Guido; Traxer, Olivier

    2017-04-05

    To evaluate in vitro the maximum pressure generated in an artificial kidney model when people of different levels of strengths used various irrigation systems. Fifteen people were enrolled and divided in 3 groups based on their strengths. Individual strength was evaluated according to the maximum pressure each participant was able to achieve using an Encore™ Inflator. The irrigation systems evaluated were: T-FlowTM Dual Port, HilineTM, continuous flow single action pumping system (SAPSTM) with the system close and open, Irri-flo IITM, a simple 60-ml syringe and PeditrolTM . Each irrigation system was connected to URF-V2 ureteroscope, which was inserted into an artificial kidney model. Each participant was asked to produce the maximum pressure possible with every irrigation device. Pressure was measured with the working channel (WC) empty, with a laser fiber and a basket inside. The highest pressure was achieved with the 60 ml-syringe system and the lowest with SAPS continuous version system (with continuous irrigation open), compared to the other irrigation devices (p< 0.0001). Irrespective of the irrigation system, there was a significant difference in the pressure between the WC empty and when occupied with the laser fiber or the basket inside it (p<0.0001). The stratification between the groups showed that the most powerful group could produce the highest pressure in the kidney model with all the irrigation devices in almost any situation. The exception to this was the T-Flow system, which was the only device where no statistical differences were detected among these groups. The use of irrigation systems can often generate excessive pressure in an artificial kidney model, especially with an unoccupied WC of the ureteroscope. Depending on the strength of force applied, very high pressure can be generated by most irrigation devices irrespective of whether the scope is occupied or not.

  20. Swing Set Irrigation System

    Directory of Open Access Journals (Sweden)

    Ambe Verma

    2015-05-01

    Full Text Available ABSTRACT India is a vast country based on agriculture and irrigation is the most important factor for agriculture. In India there are many sources provide for irrigation. Every day new technologies are emerged in the world which brings a revolutionary change in the nature of this world. day by day the energy resources used by the large population of this world are coming on the last stage This project give the idea that how the other different form of energy can be used and implemented efficiently to overcome from this problem The aim of this project is to achieve the objective of energy lasting problem which is likely to be faced over in coming decades. Energy lasting is a big problem in India. This is faced by every people who live in the country. Swing energy is the form of energy. In this paper we have represented the methodology of swing energy using for rural area of application. This paper is all about Swing Set Water Pump in which the water pump will execute with the help of a swing set of canopy type. As we need a motor to operate the water pump but in this project we use the swing in the place of motor and we use oscillatory motion of swing in the place of rotating motion of a motor. Everybody has needed the energy at an increasing rate ever since he came on the Earth. Because of this lot of energy has been exhausted and wasted. All the member are dedicated the amount of their important time to participate in multiple meetings read and research for making the content to the report. We would especially like to thanks for the efficient condition of the entire Advisory member and their experiences. This study was initial and performed within the BUDDHA INSTITUTE OF TECHNOLOGY GIDA Gorakhpur the final report represents the labour and interest of the entire member working for this project. Finally we would like to thanks to all the member of our college workshop who helped us in manufacturing of this project model.

  1. Application of SCX Language in the Compressor Anti-surge Control Program%SCX语言在压缩机防喘振控制方案中的应用

    Institute of Scientific and Technical Information of China (English)

    何世胜

    2012-01-01

    This paper introduces the application of SCX language in the anti-surge control configuration of the turbo-compressor machine train (4-in-1 machine train) in the nitric acid plant. The surge flow of the compressor has to be determined based on the physical surge test and also the information provided by the compressor vendor. After that, the surge curve is to be worked out by means of the anti surge configuration process in the SCX language. During actual production, a test on the compensated flow is to be made and a judgment to be passed to affirm if the measured value is still in the surge range and see if regulation of the compressor set is necessary. This can effectively control the surge of the compressor set so as to facilitate long-term, safe and stable operation.%介绍了SCX语言在硝酸装置中的“四合一”机组防喘振控制组态中的应用.根据喘振试验确定空压机喘振流量,结合SCX语言编写程序,作出空压机特性曲线,通过判断补偿后流量测量值位置调节机组运行,可有效地控制机组的喘振.

  2. 78 FR 3892 - Turlock Irrigation District and Modesto Irrigation District; Notice Clarifying Party Status

    Science.gov (United States)

    2013-01-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Turlock Irrigation District and Modesto Irrigation District; Notice Clarifying Party Status On January 9, 2013, the Modesto Irrigation District (Modesto) filed a motion...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-07-01

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

  4. Multiple-use Management of Irrigation Systems: Technical Constraints and Challenges

    Science.gov (United States)

    Gowing, J.; Li, Q.; Mayilswami, C.; Gunawardhana, K.

    selected distributary commands combined with longitudinal studies based on available long- term data from the full command. The reliability and duration of flows and/or storages represent a constraint to effective integration of aquaculture within the case-study sys- tems. Although fish production is non-consumptive and can be seen as a complemen- tary use of irrigation water, the challenge is to devise operating procedures that will 1 guarantee reliability and duration of flows and/or storages for fish production without increasing total water-use within the system. This is a particular problem during the rainy season when irrigation demand fluctuates widely and rapidly. The problem is ex- acerbated by deficient information systems, which constrain the scope for responsive management in these extensive canal systems. 2

  5. Storm surges in the Western Black Sea. Operational forecasting

    Directory of Open Access Journals (Sweden)

    G. MUNGOV

    2012-12-01

    Full Text Available The frequency of the storm surges in the Black Sea is lower than that in other regions of the World Ocean but they cause significant damages as the magnitude of the sea level set-up is up to 7-8 times greater than that of other sea level variations. New methods and systems for storm surge forecasting and studying their statistical characteristics are absolutely necessary for the purposes of the coastal zone management. The operational forecasting storm surge model of Meteo-France was adopted for the Black Sea in accordance with the bilateral agreement between Meteo-France and NINMH. The model was verified using tide-gauge observations for the strongest storms observed along the Bulgarian coast over the last 10 years.

  6. Observations of cyclone-induced storm surge in coastal Bangladesh

    CERN Document Server

    Chiu, Soyee

    2015-01-01

    Water level measurements from 15 tide gauges in the coastal zone of Bangladesh are analyzed in conjunction with cyclone tracks and wind speed data for 54 cyclones between 1977 and 2010. Storm surge magnitude is inferred from residual water levels computed by subtracting modeled astronomical tides from observed water levels at each station. Observed residual water levels are generally smaller than reported storm surge levels for cyclones where both are available, and many cyclones produce no obvious residual at all. Both maximum and minimum residual water levels are higher for west-landing cyclones producing onshore winds and generally diminish for cyclones making landfall on the Bangladesh coast or eastward producing offshore winds. Water levels observed during cyclones are generally more strongly influenced by tidal phase and amplitude than by storm surge alone. In only 7 of the 15 stations does the highest plausible observed water level coincide with a cyclone. While cyclone-coincident residual water level ...

  7. A numerical storm surge forecast model with Kalman filter

    Institute of Scientific and Technical Information of China (English)

    Yu Fujiang; Zhang Zhanhai; Lin Yihua

    2001-01-01

    Kalman filter data assimilation technique is incorporated into a standard two-dimensional linear storm surge model. Imperfect model equation and imperfect meteorological forcimg are accounted for by adding noise terms to the momentum equations. The deterministic model output is corrected by using the available tidal gauge station data. The stationary Kalman filter algorithm for the model domain is calculated by an iterative procedure using specified information on the inaccuracies in the momentum equations and specified error information for the observations. An application to a real storm surge that occurred in the summer of 1956 in the East China Sea is performed by means of this data assimilation technique. The result shows that Kalman filter is useful for storm surge forecast and hindcast.

  8. Electromagnetic computation methods for lightning surge protection studies

    CERN Document Server

    Baba, Yoshihiro

    2016-01-01

    This book is the first to consolidate current research and to examine the theories of electromagnetic computation methods in relation to lightning surge protection. The authors introduce and compare existing electromagnetic computation methods such as the method of moments (MOM), the partial element equivalent circuit (PEEC), the finite element method (FEM), the transmission-line modeling (TLM) method, and the finite-difference time-domain (FDTD) method. The application of FDTD method to lightning protection studies is a topic that has matured through many practical applications in the past decade, and the authors explain the derivation of Maxwell's equations required by the FDTD, and modeling of various electrical components needed in computing lightning electromagnetic fields and surges with the FDTD method. The book describes the application of FDTD method to current and emerging problems of lightning surge protection of continuously more complex installations, particularly in critical infrastructures of e...

  9. Assessment of irrigation dynamics in magnetic-resonance guided laser induced thermal therapy (MRgLITT).

    Science.gov (United States)

    Sinha, Saurabh; Hargreaves, Eric; Patel, Nitesh V; Danish, Shabbar F

    2015-03-01

    Magnetic-Resonance Guided Laser-Induced Thermal Therapy (MRgLITT) is a minimally-invasive ablation procedure for treating intracranial pathology using laser energy delivered through a fiber-optic. Saline irrigation is used to cool the fiber-optic, but factors affecting irrigation efficacy are not well studied, and quantitative information regarding irrigation speed and volume during MRgLITT procedures have not been reported. Here, we aimed to characterize variables affecting irrigation efficacy in MRgLITT. We investigated the irrigation setup of the Visualase thermal therapy system during MRgLITT procedures (Visualase Inc., Houston, TX). Using the system's peristaltic pump, irrigation flow rate was quantitated by measuring volume over five one-minute intervals. Pump settings 1-10 were assessed with and without the position-locking, resistance-imparting bone anchor in both single and double-catheter setups. Multiple tightness settings of the bone anchor were tested, and flow rates were analyzed. Rate of flow increased non-linearly with pump setting (F(1,4) = 2168.86; P irrigation speeds in achieving optimal ablation volumes. © 2015 Wiley Periodicals, Inc.

  10. Community health facility preparedness for a cholera surge in Haiti.

    Science.gov (United States)

    Mobula, Linda Meta; Jacquet, Gabrielle A; Weinhauer, Kristin; Alcidas, Gladys; Thomas, Hans-Muller; Burnham, Gilbert

    2013-01-01

    With increasing population displacement and worsening water insecurity after the 2010 earthquake, Haiti experienced a large cholera outbreak. Our goal was to evaluate the strengths and weaknesses of seven community health facilities' ability to respond to a surge in cholera cases. Since 2010, Catholic Relief Services (CRS) with a number of public and private donors has been working with seven health facilities in an effort to reduce morbidity and mortality from cholera infection. In November 2012, CRS through the Centers for Disease Control and Prevention (CDC)'s support, asked the Johns Hopkins Center for Refugee and Disaster Response to conduct a cholera surge simulation tabletop exercise at these health facilities to improve each facility's response in the event of a cholera surge. Using simulation development guidelines from the Pan American Health Organization and others, a simulation scenario script was produced that included situations of differing severity, supply chain, as well as a surge of patients. A total of 119 hospital staff from seven sites participated in the simulation exercise including community health workers, clinicians, managers, pharmacists, cleaners, and security guards. Clinics that had challenges during the simulated clinical care of patients were those that did not appropriately treat all cholera patients according to protocol, particularly those that were vulnerable, those that would need additional staff to properly treat patients during a surge of cholera, and those that required a better inventory of supplies. Simulation-based activities have the potential to identify healthcare delivery system vulnerabilities that are amenable to intervention prior to a cholera surge.

  11. Wave-Tide-Surge Coupled Simulation for Typhoon Maemi

    Institute of Scientific and Technical Information of China (English)

    Byung Ho Choi; Byung Il Min; Kyeong Ok Kim; Jin Hee Yuk

    2013-01-01

    The main task of this study focuses on studying the effect of wave-current interaction on currents,storm surge and wind wave as well as effects of current induced wave refraction and current on waves by using numerical models which consider the bottom boundary layer and sea surface roughness parameter for shallow and smooth bed area around Korean Peninsula.The coupled system (unstructured-mesh SWAN wave and ADCIRC) run on the same unstructured mesh.This identical and homogeneous mesh allows the physics of wave-circulation interactions to be correctly resolved in both models.The unstructured mesh can be applied to a large domain allowing all energy from deep to shallow waters to be seamlessly followed.There is no nesting or overlapping of structured wave meshes,and no interpolation is required.In response to typhoon Maemi (2003),all model components were validated independently,and shown to provide a faithful representation of the system's response to this storm.The waves and storm surge were allowed to develop on the continental shelf and interact with the complex nearshore environment.The resulting modeling system can be used extensively for prediction of the typhoon surge.The result show that it is important to incorporate the wave-current interaction effect into coastal area in the wave-tide-surge coupled model.At the same time,it should consider effects of depth-induced wave breaking,wind field,currents and sea surface elevation in prediction of waves.Specially,we found that:(1) wave radiation stress enhanced the current and surge elevation otherwise wave enhanced nonlinear bottom boundary layer decreased that,(2) wind wave was significantly controlled by sea surface roughness thus we cautiously took the experimental expression.The resulting modeling system can be used for hindcasting (prediction) the wave-tide-surge coupled environments at complex coastline,shallow water and fine sediment area like areas around Korean Peninsula.

  12. Sustainability of irrigated crops under future climate: the interplay of irrigation strategies and cultivar responses

    Science.gov (United States)

    De Lorenzi, F.; Bonfante, A.; Alfieri, S.; Patanè, C.; Basile, A.; Di Tommasi, P.; Monaco, E.; Menenti, M.

    2012-04-01

    Climate evolution will cause significant changes in the quality and availability of water resources, affecting many sectors including food production, where available water resources for irrigation play a crucial role. Strategies focused on managing and conserving water are one way to deal with the impact; moreover concurring adaptation measurements will be needed to cope with the foreseen decline of water resource. This work deals with i) the impacts of climate change on water requirements of an horticultural crop, determined in an irrigated district in Southern Italy, ii) the possible irrigation scheduling options and their sustainability in the future, iii) the adaptation measurements that can be undertaken to protect production, relying on intra-specific biodiversity of agricultural crops. Two climate scenarios were considered: present climate (1961-90) and future climate (2021-2050), the former from climatic statistics, and the latter from statistical downscaling of general circulation models (AOGCM). Climatic data set consists of daily time series of maximum and minimum temperature, and rainfall on a grid with spatial resolution of 35 km. The analysis of climate scenarios showed that significant increases in summer maximum daily temperature could be expected in 2021-2050 period. Soil water regime was determined by means of a mechanistic model (SWAP) of water flow in the soil-plant-atmosphere system. Twenty? soil units were identified in the district (in Sele Plain, Campania Region) and simulations were performed accounting for hydro-pedological properties of different soil units. Parameters of a generic tomato crop, in a rotation typical of the area, were used in simulations. Soil water balance was simulated in the present and future climate, both with optimal water availability and under constrains that irrigation schemes will pose. Indicators of soil water availability were calculated, in terms of soil water or evapotranspiration deficit. For several tomato

  13. Suspension-Driven Gravity Surges on Horizontal Surfaces: Effect of the Initial Shape

    Science.gov (United States)

    Zgheib, Nadim; Bonometti, Thomas; Balachandar, S.

    2016-11-01

    We present results from fully-resolved direct numerical simulations of canonical (axisymmetric and planar) and non-canonical (rectangular) configurations of horizontal suspension-driven gravity surges. We show that the dynamics along the initial minor and major axis of a rectangular release are roughly similar to that of a planar and axisymmetric current, respectively. However, contrary to expectation, we observe under certain conditions the final extent of the deposit from finite releases to surpass that from an equivalent planar current. This is attributed to a converging flow of the particle-laden mixture towards the initial minor axis, a behaviour that was previously reported for scalar-driven currents on uniform slopes. This flow is observed to be correlated with the travelling of a perturbation wave generated at the extremity of the longest side that reaches the front of the shortest side in a finite time. A semi-empirical explicit expression (based on established relations for planar and axisymmetric currents) is proposed to predict the extent of the deposit in the entire x-y plane. Finally we observe that for the same initial volume of a suspension-driven gravity surge, a release of larger initial horizontal aspect-ratio is able to retain particles in suspension for longer periods of time. ExxonMobil Upstream Research (EM 09296); NSF (OISE-0968313); CALMIP (P1525).

  14. Into the Surge of Network-driven Innovation

    DEFF Research Database (Denmark)

    Østergaard, Claus Møller; Rosenstand, Claus Andreas Foss; Gertsen, Frank

    2013-01-01

    The ambition of this paper is to provide a better theoretical understanding of innovation by framing it in a long historical, economical, and societal perspective. The research question of the paper is: What characterize the historical surges of innovation? Based on previous works and research...... this is examined from the 1880’s up until today. The contribution of the paper is a societal perspective on innovation, where the difference between industrial society and knowledge society leads into the surge of network-driven innovation. Network-driven innovation is unfolded on top of the known cost- driven...

  15. Probabilistic Storm Surge Hazard Assessment in the French West Indies

    Science.gov (United States)

    Krien, Y.; Dudon, B.; Roger, J.; Zahibo, N.; Arnaud, G.

    2016-12-01

    The French West Indies are prone to hurricanes formed over the warm tropical waters of the Atlantic Ocean and Caribbean Sea. These events can have great consequences in terms of human, property, and economic losses. Storm surge hazard assessment is therefore required to provide guidance to emergency managers and decision-makers. By combining statistical-deterministic approaches and wave-current coupled models, we assessed storm surge hazard in Guadeloupe and Martinique islands. We present here the methodology, the results, as well as the on-going work on the impact of climate change in the framework of the FEDER-funded project C3AF.

  16. A High Resolution Forecast Model of Storm Surge Inundation

    Institute of Scientific and Technical Information of China (English)

    LIU Juan; JIANG Wensheng; SUN Wenxin; WANG Yongzhi

    2005-01-01

    In order to forecast storm surge inundation, a two-dimensional model is established. In the model, an alternating computation sequence method is used to solve the governing equations, and the dry and wet method is introduced to treat the moving boundary. This model is easy to use. It has a friendly input interface and Arcview GIS is used as the output interface. The model is applied to the Shantou area to simulate the storm surge elevations and inundations caused by Typhoons 6903 ane 0104 using the same relevant parameters. The calculated results agree well with the observations.

  17. Surge of the Bivachny Glacier in 2012–2015

    OpenAIRE

    V. M. Kotlyakov; L. V. Desinov; V. A. Rudakov

    2015-01-01

    The surge of the Bivachny Glacier that occurred in 2012–2015 is analyzed with the use of photographing performed from International Space Station in 2001–2015 together with data of the satellite monitoring of 1972–2000. This surge happened in 31 years after the similar previous event of 1972–1976. Dynamics of numerous glacier branches causing activation of the lower glacier part that is so called “dead” zone (more than 7 km in length) is shown. Just before its stop the front part of the surgi...

  18. Modelling of root ABA synthesis, stomatal conductance, transpiration and potato production under water saving irrigation regimes

    DEFF Research Database (Denmark)

    Plauborg, Finn; Abrahamsen, Per; Gjettermann, Birgitte

    2010-01-01

    a central role in reducing crop transpiration. This paper presented a mechanistic model (Daisy) developed based on data obtained in the SAFIR project on measured leaf gas exchange and soil water dynamics in irrigated potato crops grown in a semi-field environment subjected to different irrigation regimes...... Daisy model is capable of simulating the mechanisms underlying the water saving effects of the partial root-zone drying (PRD) irrigation as compared with the conventional full irrigation (FI). However the simulated effect on both crop yield and water use in this particular experiment was negligible......Application of water saving irrigation strategies in agriculture has become increasingly important. Both modelling and experimental work are needed to gain more insights into the biological and physical mechanisms in the soil-plant system, which regulates water flow in the system and plays...

  19. Ground-water resources of Riverton irrigation project area, Wyoming

    Science.gov (United States)

    Morris, Donald Arthur; Hackett, O.M.; Vanlier, K.E.; Moulder, E.A.; Durum, W.H.

    1959-01-01

    The Riverton irrigation project area is in the northwestern part of the Wind River basin in west-central Wyoming. Because the annual precipitation is only about 9 inches, agriculture, which is the principal occupation in the area, is dependent upon irrigation. Irrigation by surface-water diversion was begum is 1906; water is now supplied to 77,716 acres and irrigation has been proposed for an additional 31,344 acres. This study of the geology and ground-water resources of the Riverton irrigation project, of adjacent irrigated land, and of nearby land proposed for irrigation was begun during the summer of 1948 and was completed in 1951. The purpose of the investigation was to evaluate the ground-water resources of the area and to study the factors that should be considered in the solution of drainage and erosional problems within the area. The Riverton irrigation project area is characterized by flat to gently sloping stream terraces, which are flanked by a combination of badlands, pediment slopes, and broad valleys. These features were formed by long-continued erosion in an arid climate of the essentially horizontal, poorly consolidated beds of the Wind River formation. The principal streams of the area flow south-eastward. Wind River and Fivemile Creek are perennial streams and the others are intermittent. Ground-water discharge and irrigation return flow have created a major problem in erosion control along Fivemile Creek. Similar conditions might develop along Muddy and lower Cottonwood Creeks when land in their drainage basins is irrigated. The bedrock exposed in the area ranges in age from Late Cretaceous to early Tertiary (middle Eocene). The Wind River formation of early and middle Eocene age forms the uppermost bedrock formation in the greater part of the area. Unconsolidated deposits of Quaternary age, which consist of terrace gravel, colluvium, eolian sand and silt. and alluvium, mantle the Wind River formation in much of the area. In the irrigated parts

  20. NUMERICAL STUDY OF THE INFLUENCE OF WAVES AND TIDE-SURGE INTERACTION ON TIDE-SURGES IN THE BOHAI SEA

    Institute of Scientific and Technical Information of China (English)

    尹宝树; 侯一筠; 程明华; 苏京志; 林明祥; 李明悝; M.I.El-Sabh

    2001-01-01

    Abstract The author's combined numerical model consisting of a third generation shallow water wave model and a 3-D tide-surge model with wave-dependent surface wind stress were used to study the influence of waves on fide-surge motion. For the typical weather case, in this study, the magnitude and mechanism of the influence of waves on tide-surges in the Bohai Sea were revealed for the first time. The results showed that although consideration of the wave-dependent surface wind stresses raise slightly the traditional surface wind stress, due to the accumulated effects, the computed results are improved on the whole. Storm level maximum modulation can reach 0.4 m. The results computed by the combined model agreed well with the measured data.

  1. NUMERICAL STUDY OF THE INFLUENCE OF WAVES AND TIDE- SURGE INTERACTION ON TIDE-SURGES IN THE BOHAI SEA

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The author's combined numerical model consisting of a third generation shallow water wave model and a 3-D tide-surge model with wave-dependent surface wind stress were used to study the influence of waves on tide-surge motion. For the typical weather case, in this study, the magnitude and mechanism of the influence of waves on tide-surges in the Bohai Sea were revealed for the first time. The results showed that although consideration of the wave-dependent surface wind stresses raise slightly the traditional surface wind stress, due to the accumulated effects, the computed results are improved on the whole. Storm level maximum modulation can reach 0.4 m. The results computed by the combined model agreed well with the measured data.

  2. Stall/surge dynamics of a multi-stage air compressor in response to a load transient of a hybrid solid oxide fuel cell-gas turbine system

    Science.gov (United States)

    Azizi, Mohammad Ali; Brouwer, Jacob

    2017-10-01

    A better understanding of turbulent unsteady flows in gas turbine systems is necessary to design and control compressors for hybrid fuel cell-gas turbine systems. Compressor stall/surge analysis for a 4 MW hybrid solid oxide fuel cell-gas turbine system for locomotive applications is performed based upon a 1.7 MW multi-stage air compressor. Control strategies are applied to prevent operation of the hybrid SOFC-GT beyond the stall/surge lines of the compressor. Computational fluid dynamics tools are used to simulate the flow distribution and instabilities near the stall/surge line. The results show that a 1.7 MW system compressor like that of a Kawasaki gas turbine is an appropriate choice among the industrial compressors to be used in a 4 MW locomotive SOFC-GT with topping cycle design. The multi-stage radial design of the compressor enhances the ability of the compressor to maintain air flow rate during transient step-load changes. These transient step-load changes are exhibited in many potential applications for SOFC/GT systems. The compressor provides sustained air flow rate during the mild stall/surge event that occurs due to the transient step-load change that is applied, indicating that this type of compressor is well-suited for this hybrid application.

  3. Teaching transanal irrigation for functional bowel disorders.

    Science.gov (United States)

    Coggrave, Maureen; Norton, Christine

    Transanal irrigation of the bowel in the management of functional bowel disorders is currently receiving increased attention following the recent introduction of the Peristeen irrigation kit (Coloplast Ltd) in April 2007. Irrigation provides a welcome additional choice in the limited range of available interventions for the management of these patients. However, evidence to support clinical practice around irrigation is limited and nursing knowledge and experience of irrigation is only just developing. This paper reports a series of master classes conducted to support and develop the use of irrigation in the UK, and demonstrates the value of the master class as an educational tool when introducing a novel therapy.

  4. Formation and removal of apical vapor lock during syringe irrigation: a combined experimental and Computational Fluid Dynamics approach

    NARCIS (Netherlands)

    Boutsioukis, C.; Kastrinakis, E.; Lambrianidis, T.; Verhaagen, B.; Versluis, M.; Sluis, van der L.W.M.

    2014-01-01

    Aim (i) To evaluate the effect of needle type and insertion depth, root canal size and irrigant flow rate on the entrapment of air bubbles in the apical part of a root canal (apical vapor lock) during syringe irrigation using experiments and a Computational Fluid Dynamics (CFD) model, (ii) to invest

  5. Phosphorus losses from an irrigated watershed in the Northwestern U.S.: Case study of the Upper Snake Rock Watershed

    Science.gov (United States)

    Watersheds utilizing surface water for irrigation often return a portion of the water to a water body. This irrigation return flow often includes sediment and nutrients that reduce the quality of the receiving water body. Research in the 82,000 ha Upper Snake Rock (USR) watershed from 2005 to 2008 s...

  6. Formation and removal of apical vapor lock during syringe irrigation : a combined experimental and Computational Fluid Dynamics approach

    NARCIS (Netherlands)

    Boutsioukis, C.; Kastrinakis, E.; Lambrianidis, T.; Verhaagen, B.; Versluis, M.; van der Sluis, L. W. M.

    2014-01-01

    Aim(i) To evaluate the effect of needle type and insertion depth, root canal size and irrigant flow rate on the entrapment of air bubbles in the apical part of a root canal (apical vapor lock) during syringe irrigation using experiments and a Computational Fluid Dynamics (CFD) model, (ii) to investi

  7. The use and re-use of unsustainable groundwater for irrigation: a global budget

    Science.gov (United States)

    Grogan, Danielle S.; Wisser, Dominik; Prusevich, Alex; Lammers, Richard B.; Frolking, Steve

    2017-03-01

    Depletion of groundwater aquifers across the globe has become a significant concern, as groundwater is an important and often unsustainable source of irrigation water. Simultaneously, the field of water resource management has seen a lively debate over the concepts and metrics used to assess the downstream re-use of agricultural runoff, with most studies focusing on surface water balances. Here, we bring these two lines of research together, recognizing that depletion of aquifers leads to large amounts of groundwater entering surface water storages and flows by way of agricultural runoff. While it is clear that groundwater users will be impacted by reductions in groundwater availability, there is a major gap in our understanding of potential impacts downstream of groundwater pumping locations. We find that the volume of unsustainable groundwater that is re-used for irrigation following runoff from agricultural systems is nearly as large as the volume initially extracted from reservoirs for irrigation. Basins in which the volume of irrigation water re-used is equal to or greater than the volume of water initially used (which is possible due to multiple re-use of the same water) contain 33 million hectares of irrigated land and are home to 1.3 billion people. Some studies have called for increasing irrigation efficiency as a solution to water shortages. We find that with 100% irrigation efficiency, global demand for unsustainable groundwater is reduced by 52%, but not eliminated. In many basins, increased irrigation efficiency leads to significantly decreased river low flows; increasing irrigation efficiency to 70% globally decreases total surface water supplies by ∽600 km3 yr-1. These findings illustrate that estimates of aquifer depletion alone underestimate the importance of unsustainable groundwater to sustaining surface water systems and irrigated agriculture.

  8. Irrigation in dose assessments models

    Energy Technology Data Exchange (ETDEWEB)

    Bergstroem, Ulla; Barkefors, Catarina [Studsvik RadWaste AB, Nykoeping (Sweden)

    2004-05-01

    SKB has carried out several safety analyses for repositories for radioactive waste, one of which was SR 97, a multi-site study concerned with a future deep bedrock repository for high-level waste. In case of future releases due to unforeseen failure of the protective multiple barrier system, radionuclides may be transported with groundwater and may reach the biosphere. Assessments of doses have to be carried out with a long-term perspective. Specific models are therefore employed to estimate consequences to man. It has been determined that the main pathway for nuclides from groundwater or surface water to soil is via irrigation. Irrigation may cause contamination of crops directly by e.g. interception or rain-splash, and indirectly via root-uptake from contaminated soil. The exposed people are in many safety assessments assumed to be self-sufficient, i.e. their food is produced locally where the concentration of radionuclides may be the highest. Irrigation therefore plays an important role when estimating consequences. The present study is therefore concerned with a more extensive analysis of the role of irrigation for possible future doses to people living in the area surrounding a repository. Current irrigation practices in Sweden are summarised, showing that vegetables and potatoes are the most common crops for irrigation. In general, however, irrigation is not so common in Sweden. The irrigation model used in the latest assessments is described. A sensitivity analysis is performed showing that, as expected, interception of irrigation water and retention on vegetation surfaces are important parameters. The parameters used to describe this are discussed. A summary is also given how irrigation is proposed to be handled in the international BIOMASS (BIOsphere Modelling and ASSessment) project and in models like TAME and BIOTRAC. Similarities and differences are pointed out. Some numerical results are presented showing that surface contamination in general gives the

  9. Influence of different operating conditions on irrigation uniformity with microperforated tapes

    Science.gov (United States)

    Moreno Pizani, María Alejandra; Jesús Farías Ramírez, Asdrúbal

    2013-04-01

    Irrigated agriculture is a safe alternative to meet the growing demand for food. Numerous studies show that proper management of localized irrigation can increase crop yields and reduce soil salinization. Therefore, periodic field systems irrigation assessments are needed in order to optimize the use efficiency of irrigation water, as well as, to increase the agricultural area covered by the same amount of water and to reduce the environmental impact. It was assessed the behavior of micro perforated tapes under different operating conditions, crops and regions of Venezuela. Evaluations were made on irrigated areas using Santeno ® Type I tape with the following crops: Banana (Musa sp), lettuce (Lactuca sativa L.), carrot (Daucus carota L) and forage sugar cane (Saccharum officinarum). In the other hand, Santeno ® Type II tape was used with papaya (Carica papaya L.) and melon (Cucumis melo L.) crops (the last crop using inverted irrigation tape). The procedures used for sampling and determining the uniformity indices of the system were performed using a series of adjustments to the methodology proposed by Keller and Karmeli (1975), Deniculi (1980) and De Santa and De Juan (1993), in order to increase the number of observations as a function of irrigation time. The calculated irrigation uniformity indices were as follow: Distribution Coefficient (UD), Uniformity Coefficient (CUC), Coefficient of Variation of Flows (CV) and Statistical Uniformity Coefficient (Us). The indices characterization was made according to Merrian and Keller (1978); Bralts (1986); Pizarro (1990) y ASAE (1996), respectively. The results showed that the irrigation uniformity for the evaluated systems varied from excellent to unacceptable, mainly due to the lack of maintenance and the absent of manometric connectors. Among the findings, it is possible to highlight the need for technical support to farmers, both in the installation, management and maintenance of irrigation systems. In this sense

  10. Modelling and Quasilinear Control of Compressor Surge and Rotating Stall Vibrations

    Directory of Open Access Journals (Sweden)

    Ranjan Vepa

    2010-01-01

    Full Text Available An unsteady nonlinear and extended version of the Moore-Greitzer model is developed to facilitate the synthesis of a quasilinear stall vibration controller. The controller is synthesised in two steps. The first step defines the equilibrium point and ensures that the desired equilibrium point is stable. In the second step, the margin of stability at the equilibrium point is tuned or increased by an appropriate feedback of change in the mass flow rate about the steady mass flow rate at the compressor exit. The relatively simple and systematic non-linear modelling and linear controller synthesis approach adopted in this paper clearly highlights the main features on the controller that is capable of inhibiting compressor surge and rotating stall vibrations. Moreover, the method can be adopted for any axial compressor provided its steady-state compressor and throttle maps are known.

  11. Aging assessment of surge protective devices in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J.F.; Subudhi, M. [Brookhaven National Lab., Upton, NY (United States); Carroll, D.P. [Florida Univ., Gainesville, FL (United States)

    1996-01-01

    An assessment was performed to determine the effects of aging on the performance and availability of surge protective devices (SPDs), used in electrical power and control systems in nuclear power plants. Although SPDs have not been classified as safety-related, they are risk-important because they can minimize the initiating event frequencies associated with loss of offsite power and reactor trips. Conversely, their failure due to age might cause some of those initiating events, e.g., through short circuit failure modes, or by allowing deterioration of the safety-related component(s) they are protecting from overvoltages, perhaps preventing a reactor trip, from an open circuit failure mode. From the data evaluated during 1980--1994, it was found that failures of surge arresters and suppressers by short circuits were neither a significant risk nor safety concern, and there were no failures of surge suppressers preventing a reactor trip. Simulations, using the ElectroMagnetic Transients Program (EMTP) were performed to determine the adequacy of high voltage surge arresters.

  12. Why Teen Mental Ability Surges While Brain Shrinks

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_166310.html Why Teen Mental Ability Surges While Brain Shrinks Researchers say they may have answer to ... behavior keep scaling up," he said. So while teens lose brain volume and girls have lower brain volume than ...

  13. 14 CFR 33.65 - Surge and stall characteristics.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Surge and stall characteristics. 33.65 Section 33.65 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... stall characteristics. When the engine is operated in accordance with operating instructions required...

  14. Monitoring Inland Storm Surge and Flooding from Hurricane Rita

    Science.gov (United States)

    McGee, Benton D.; Tollett, Roland W.; Mason, Jr., Robert R.

    2006-01-01

    Pressure transducers (sensors) and high-water marks were used to document the inland water levels related to storm surge generated by Hurricane Rita in southwestern Louisiana and southeastern Texas. On September 22-23, 2005, an experimental monitoring network of sensors was deployed at 33 sites over an area of about 4,000 square miles to record the timing, extent, and magnitude of inland hurricane storm surge and coastal flooding. Sensors were programmed to record date and time, temperature, and barometric or water pressure. Water pressure was corrected for changes in barometric pressure and salinity. Elevation surveys using global-positioning systems and differential levels were used to relate all storm-surge water-level data, reference marks, benchmarks, sensor measuring points, and high-water marks to the North American Vertical Datum of 1988 (NAVD 88). The resulting data indicated that storm-surge water levels over 14 feet above NAVD 88 occurred at three locations, and rates of water-level rise greater than 5 feet per hour occurred at three locations near the Louisiana coast.

  15. ISSN 2073-9990 East Cent. Afr. J. surg

    African Journals Online (AJOL)

    Hp 630 Dual Core

    COSECSA/ASEA Publication - East and Central African Journal of Surgery. December 2016; Vol. .... shorter duration (median of 20 weeks vs. 3.5 weeks, p 0.029). .... inguinal hernia in children: laparoscopic or open? Eur J Ped Surg 2011; 21: ...

  16. Debris entrainment and landform genesis during tidewater glacier surges

    Science.gov (United States)

    Lovell, Harold; Fleming, Edward J.; Benn, Douglas I.; Hubbard, Bryn; Lukas, Sven; Rea, Brice R.; Noormets, Riko; Flink, Anne E.

    2015-08-01

    The englacial entrainment of basal debris during surges presents an opportunity to investigate processes acting at the glacier bed. The subsequent melt-out of debris-rich englacial structures during the quiescent phase produces geometrical ridge networks on glacier forelands that are diagnostic of surge activity. We investigate the link between debris entrainment and proglacial geomorphology by analyzing basal ice, englacial structures, and ridge networks exposed at the margins of Tunabreen, a tidewater surge-type glacier in Svalbard. The basal ice facies display clear evidence for brittle and ductile tectonic deformation, resulting in overall thickening of the basal ice sequence. The formation of debris-poor dispersed facies ice is the result of strain-induced metamorphism of meteoric ice near the bed. Debris-rich englacial structures display a variety of characteristics and morphologies and are interpreted to represent the incorporation and elevation of subglacial till via the squeezing of till into basal crevasses and hydrofracture exploitation of thrust faults, reoriented crevasse squeezes, and preexisting fractures. These structures are observed to melt-out and form embryonic geometrical ridge networks at the base of a terrestrially grounded ice cliff. Ridge networks are also located at the terrestrial margins of Tunabreen, neighboring Von Postbreen, and in a submarine position within Tempelfjorden. Analysis of network characteristics allows these ridges to be linked to different formational mechanisms of their parent debris-rich englacial structures. This in turn provides an insight into variations in the dominant tectonic stress regimes acting across the glacier during surges.

  17. On the Response of Interleaved Transformer Windings to Surge Voltages

    DEFF Research Database (Denmark)

    Pedersen, A.

    1963-01-01

    The high series capacitance theory for the response of interleaved transformer windings to surge voltages is criticized from the point of view that an increased series capacitance as a result of interleaving is incompatible with the concept of a pure capacitive initial voltage distribution. A new...

  18. Wall shear stress effects of different endodontic irrigation techniques and systems.

    Science.gov (United States)

    Goode, Narisa; Khan, Sara; Eid, Ashraf A; Niu, Li-na; Gosier, Johnny; Susin, Lisiane F; Pashley, David H; Tay, Franklin R

    2013-07-01

    This study examined débridement efficacy as a result of wall shear stresses created by different irrigant delivery/agitation techniques in an inaccessible recess of a curved root canal model. A reusable, curved canal cavity containing a simulated canal fin was milled into mirrored titanium blocks. Calcium hydroxide (Ca(OH)2) paste was used as debris and loaded into the canal fin. The titanium blocks were bolted together to provide a fluid-tight seal. Sodium hypochlorite was delivered at a previously-determined flow rate of 1 mL/min that produced either negligible or no irrigant extrusion pressure into the periapex for all the techniques examined. Nine irrigation delivery/agitation techniques were examined: NaviTip passive irrigation control, Max-i-Probe(®) side-vented needle passive irrigation, manual dynamic agitation (MDA) using non-fitting and well-fitting gutta-percha points, EndoActivator™ sonic agitation with medium and large points, VPro™ EndoSafe™ irrigation system, VPro™ StreamClean™ continuous ultrasonic irrigation and EndoVac apical negative pressure irrigation. Débridement efficacies were analysed with Kruskal-Wallis ANOVA and Dunn's multiple comparisons tests (α=0.05). EndoVac was the only technique that removed more than 99% calcium hydroxide debris from the canal fin at the predefined flow rate. This group was significantly different (p<0.05) from the other groups that exhibited incomplete Ca(OH)2 removal. The ability of the EndoVac system to significantly clean more debris from a mechanically inaccessible recess of the model curved root canal may be caused by robust bubble formation during irrigant delivery, creating higher wall shear stresses by a two-phase air-liquid flow phenomenon that is well known in other industrial débridement systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Estimating actual irrigation application by remotely sensed evapotranspiration observations

    NARCIS (Netherlands)

    Droogers, P.; Immerzeel, W.W.; Lorite, I.J.; SWAP, PEST

    2010-01-01

    Water managers and policy makers need accurate estimates of real (actual) irrigation applications for effective monitoring of irrigation and efficient irrigation management. However, this information is not readily available at field level for larger irrigation areas. An innovative inverse modeling

  20. Sustainable irrigation in fruit trees

    Directory of Open Access Journals (Sweden)

    Cristos Xiloyannis

    Full Text Available Water management in fruit growing, particularly in areas with high water deficit, low rainfall and limited availability of water for irrigation should aid to save water by: i the choice of high efficiency irrigation methods and their correct management; ii the proper choice of the specie, cultivar and rootstock to optimise plant water use; iii the proper choice of the architecture of the canopy and it’s correct management in order to improve water use efficiency; iv the application of regulated deficit irrigation at growth stages less sensitive to water deficit; v strengthening the role of technical assistance for a rapid transfer of knowledge to the growers on the sustainable use of water in fruit growing.

  1. Adaptive management of irrigation and crops' biodiversity: a case study on tomato

    Science.gov (United States)

    De Lorenzi, Francesca; Alfieri, Silvia Maria; Basile, Angelo; Bonfante, Antonello; Monaco, Eugenia; Riccardi, Maria; Menenti, Massimo

    2013-04-01

    We have assessed the impacts of climate change and evaluated options to adapt irrigation management in the face of predicted changes of agricultural water demand. We have evaluated irrigation scheduling and its effectiveness (versus crop transpiration), and cultivars' adaptability. The spatial and temporal variations of effectiveness and adaptability were studied in an irrigated district of Southern Italy. Two climate scenarios were considered: reference (1961-90) and future (2021-2050) climate, the former from climatic statistics, and the latter from statistical downscaling of general circulation models (AOGCM). Climatic data consist of daily time series of maximum and minimum temperature, and daily rainfall on a grid with a spatial resolution of 35 km. The work was carried out in the Destra Sele irrigation scheme (18.000 ha. Twenty-five soil units were identified and their hydrological properties were determined (measured or estimated from texture through pedo-transfer functions). A tomato crop, in a rotation typical of the area, was considered. A mechanistic model of water flow in the soil-plant-atmosphere system (SWAP) was used to study crop water requirements and water consumption. The model was calibrated and validated in the same area for many different crops. Tomato crop input data and model parameters were estimated on the basis of scientific literature and assumed to be generically representative of the species. Simulations were performed for reference and future climate, and for different irrigation scheduling options. In all soil units, six levels of irrigation volumes were applied: full irrigation (100%), deficit irrigation (80%, 60%, 40%, 20%), no irrigation. From simulation runs, indicators of soil water availability were calculated, moreover the marginal increases of transpiration per unit of irrigation volume, i.e. the effectiveness of irrigation (ΔT/I), were computed, in both climate scenarios. Indicators and marginal increases were used to

  2. Predicting paleohydraulics from storm surge and tsunami deposits: Using experiments to improve inverse model accuracy

    Science.gov (United States)

    Johnson, Joel P. L.; Delbecq, Katie; Kim, Wonsuck

    2017-04-01

    How accurately can flow depths and velocities of storm surges and tsunamis be predicted from sedimentary deposits? Inverse models have been proposed to quantify hydrodynamics from suspended sediment deposits, but assumptions about how deposit grain size distributions (GSDs) are influenced by flow characteristics remain largely untested. Using laboratory experiments, we evaluate an existing advection-settling model in which suspended sediment transport is assumed to reflect horizontal advection (constraining flow velocity) and vertical settling from the water surface (constraining depth). While the original model assumed that depth and velocity would be best predicted by the deposit D95 (the diameter for which 95% of the cumulative GSD is finer), we find that the median deposit size (D50) tends to better predict mean flow hydraulics. Two key factors influencing how flow characteristics control deposit GSDs are (a) dispersion caused by turbulence and (b) the transport distance required for suspension and settling to effectively sort grains. Deposits proximal to sediment sources primarily reflect the source GSD, while deposits farther from the source preferentially represent transport-dependent sorting. In our experimental data, transport distances longer than 1-2 advection length scales are required for the deposit GSD to reasonably predict flow depths and velocities. These results suggest ways that event deposits can be used to more accurately assess coastal risks from tsunamis and storm waves.

  3. Changing the guard: Polymer replaces porcelain for surge arresters

    Energy Technology Data Exchange (ETDEWEB)

    Skytt, T.; Gleimar, H. E. G.

    2002-07-01

    Surge arresters are safety devices which quickly and effectively limit the over voltages that can arise in transmission networks following lightning, switching and other transient events. The earliest forms of overvoltage protection, a simple air gap between electrodes, have long since been replaced by a new generation of gapless arresters with series-connected, non-linear zinc oxide varistors contained in a porcelain housing. Now these porcelain type surge arresters are being replaced by a new type, called PEXLIM (Polymeric EXcellent LIMiter), which uses the same block of zinc oxide as the porcelain type, but its housing is made of silicon rubber, a polymer. The new lightweight insulation material shows a number of properties superior to the porcelain, such as enhanced product safety and ease of handling. It is also more durable, resilient, yet solid and compact, water-repellent, lightweight, resistant to aging or light or ultra-violet radiation, as well as fire, has good electrical properties, and is environmentally friendly since it does not contain any substances harmful to the environment. These properties make this new type of surge arrester highly suitable for use in earthquake-prone areas; it can also replace more expensive and maintenance-intensive equipment. Having successfully broken into the lower voltage systems, these new type of surge arresters are now rapidly gaining ground at the higher voltage levels. ABB, the developer of PEXLIM, has already supplied these arresters to North America for use in an 800-kV grid. As further proof of its growing popularity, last year PEXLIM made up over half of the surge arrester production for applications up to and including 245 kV. 1 tab., 6 figs.

  4. A basis function approach for exploring the seasonal and spatial features of storm surge events

    Science.gov (United States)

    Wu, Wenyan; Westra, Seth; Leonard, Michael

    2017-07-01

    Storm surge is a significant contributor to flooding in coastal and estuarine regions. To represent the statistical characteristics of storm surge over a climatologically diverse region, we propose the use of basis functions that capture the temporal progression of individual storm surge events. This extends statistical analyses of surge from considering only the peak to a more multifaceted approach that also includes decay rate and duration. Our results show that there is seasonal variation in storm surge along the Australian coastline. During the dominant storm surge seasons, the peak and duration of storm surge events tend to increase simultaneously at a number of locations, with implications for flood damage assessments and evacuation planning. By combining the dynamic and statistical features of storm surge, it is possible to better understand the factors that can lead to flood risk along the coastline, including estuarine areas that are also affected by fluvial floods.

  5. Storm surge in the Bay of Bengal and Arabian Sea: The problem and its prediction

    Digital Repository Service at National Institute of Oceanography (India)

    Dube, S.K.; Rao, A.D.; Sinha, P.C.; Murty, T.S.; Bahulayan, N.

    India and its neighbourhood is threatened by the possibility of storm surge floods whenever a tropical cyclone approaches. Storm surge disasters cause heavy loss of life and property, damage to the coastal structures and agriculture nwhich lead...

  6. Spatial variability of available water and micro-sprinkler irrigation in cambisol

    Directory of Open Access Journals (Sweden)

    Larissa Luana Nicodemos Ferreira

    Full Text Available ABSTRACT The technology of irrigation is vital for agricultural production. Thus, description of spatial patterns of both water application and available water capacity in the soil, as well as their interactions, is essential to maximize efficiency of water use in irrigated areas. The objective of this study was to analyze spatial variability of available water capacity in the soil and water application via irrigation using geostatistics. The experiment was conducted in a commercial mango orchard in Cambisol irrigated by micro sprinkler system, in the municipality of Alto do Rodrigues, RN. Analyses of descriptive statistics and geostatistics were performed using the programs GeoR and GS+. Geostatistics was found suitable for describing the structure of spatial dependence of available water capacity in the soil and the flow rate distributed in the area by sprinklers. Moreover, even with good results for Christiansen Uniformity Coefficient (CU and Distribution Uniformity Coefficient (DU, the area showed spatial variability of flow rate.

  7. AGROCLIMATIC DETERMINANTS OF IRRIGATION NEEDS

    Directory of Open Access Journals (Sweden)

    Leszek Łabędzki

    2016-05-01

    Full Text Available The paper is a review of the so far used in Poland methods and criteria for assessing the needs of irrigation for planning purposes, the assessment because of the agroclimatic conditions and taking into account the soil water retention. Irrigation needs of the most are determined taking into account crop water deficits. This is the factor that is characterized by a shortage of precipitation in relation to the water requirements of crops. Some methods use only the meteorological parameters that determine the state of the atmosphere-soil-plant system, and some also take into account soil water retention and its availability for plants.

  8. A Prospective Randomized Control Trial to Study the Role of Intraperitoneal Irrigation with Normal Saline in Reduction of Postoperative Pain In Patients Undergoing Laparoscopic Cholecystectomy

    Directory of Open Access Journals (Sweden)

    Pankaj Shivhare

    2014-08-01

    Results: Abdominal pain was worst during the first 24 hours after laparoscopic cholecystectomy. At 6, 12 and 24 hrs, group A exhibited significantly less abdominal pain than group B. Group A also experienced less shoulder tip pain during the first postoperative day as compared to the control group. Conclusion: Intraperitoneal irrigation with normal saline is effective in reducing postoperative abdominal and shoulder tip pain following laparoscopic cholecystectomy. [Arch Clin Exp Surg 2014; 3(4.000: 213-219

  9. Sustainable management after irrigation system transfer : experiences in Colombia - the RUT irrigation district

    NARCIS (Netherlands)

    Urrutia Cobo, N.

    2006-01-01

    Colombiais a tropical country located in South America. It has a total area of 114 million ha. In Colombia two irrigation sectors are distinguished: the small-scale irrigation and the large-scale irrigation sector. The small-scale irrigation sector is developed on lands locat

  10. Sustainable management after irrigation system transfer : experiences in Colombia - the RUT irrigation district

    NARCIS (Netherlands)

    Urrutia Cobo, N.

    2006-01-01

    Colombiais a tropical country located in South America. It has a total area of 114 million ha. In Colombia two irrigation sectors are distinguished: the small-scale irrigation and the large-scale irrigation sector. The small-scale irrigation sector is developed on lands locat

  11. Sustainable management after irrigation system transfer : experiences in Colombia - the RUT irrigation district

    NARCIS (Netherlands)

    Urrutia Cobo, N.

    2006-01-01

    Colombiais a tropical country located in South America. It has a total area of 114 million ha. In Colombia two irrigation sectors are distinguished: the small-scale irrigation and the large-scale irrigation sector. The small-scale irrigation sector is developed on lands

  12. 75 FR 43958 - Turlock Irrigation District and Modesto Irrigation District; Notice of Application for Amendment...

    Science.gov (United States)

    2010-07-27

    ... Energy Regulatory Commission Turlock Irrigation District and Modesto Irrigation District; Notice of...: May 24, 2010. d. Applicant: Turlock Irrigation District and Modesto Irrigation District. e. Name of.... g. Filed Pursuant to: Federal Power Act, 16 USC 791a-825r. h. Applicant Contact: Turlock...

  13. Cotton irrigation timing with variable seasonal irrigation capacities in the Texas south plains.

    Science.gov (United States)

    Within the Ogallala Aquifer Region of Texas, the irrigation capacity (IC) for a given field often changes within a growing season due to seasonal depletion of the aquifer, in season changes in crop irrigation needs in dry years, or consequences of irrigation volume limits imposed by irrigation distr...

  14. 75 FR 35778 - Modesto Irrigation District and Turlock Irrigation District; Notice of Preliminary Permit...

    Science.gov (United States)

    2010-06-23

    ... Energy Regulatory Commission Modesto Irrigation District and Turlock Irrigation District; Notice of... Competing Applications June 16, 2010. On February 1, 2010, Modesto Irrigation District and Turlock Irrigation District filed an application for a preliminary permit, pursuant to section 4(f) of the...

  15. SURDEV: surface irrigation software; design, operation, and evaluation of basin, border, and furrow irrigation

    NARCIS (Netherlands)

    Jurriëns, M.; Zerihun, D.; Boonstra, J.; Feyen, J.

    2001-01-01

    SURDEV is a computer package for the design, operation, and evaluation of surface irrigation. SURDEV combines three sub-programs: BASDEV (for basin irrigation), FURDEV (for furrow irrigation), and BORDEV for (border irrigation). This combination enables the user to simulate many of the problems invo

  16. Modernisation Strategy for National Irrigation Systems in the Philippines: Balanac and Sta. Maria River Irrigation Systems

    NARCIS (Netherlands)

    Delos Reyes, M.L.F.

    2017-01-01

    This book examines the nature and impact of irrigation system rehabilitation on increasing the actual area irrigated by the publicly funded canal irrigation systems of the Philippines. It proposes a system diagnosis approach for the development of a more appropriate and climate-smart irrigation

  17. SURDEV: surface irrigation software; design, operation, and evaluation of basin, border, and furrow irrigation

    NARCIS (Netherlands)

    Jurriëns, M.; Zerihun, D.; Boonstra, J.; Feyen, J.

    2001-01-01

    SURDEV is a computer package for the design, operation, and evaluation of surface irrigation. SURDEV combines three sub-programs: BASDEV (for basin irrigation), FURDEV (for furrow irrigation), and BORDEV for (border irrigation). This combination enables the user to simulate many of the problems

  18. Sustainable management after irrigation system transfer : experiences in Colombia - the RUT irrigation district

    NARCIS (Netherlands)

    Urrutia Cobo, N.

    2006-01-01

    Colombiais a tropical country located in South America. It has a total area of 114 million ha. In Colombia two irrigation sectors are distinguished: the small-scale irrigation and the large-scale irrigation sector. The small-scale irrigation sector is developed on lands locat

  19. Measuring Transpiration to Regulate Winter Irrigation Rates

    Energy Technology Data Exchange (ETDEWEB)

    Samuelson, Lisa [Auburn University

    2006-11-08

    Periodic transpiration (monthly sums) in a young loblolly pine plantation between ages 3 and 6 was measured using thermal dissipation probes. Fertilization and fertilization with irrigation were better than irrigation alone in increasing transpiration of young loblolly pines during winter months, apparently because of increased leaf area in fertilized trees. Irrigation alone did not significantly increase transpiration compared with the non-fertilized and non-irrigated control plots.

  20. Brief Communication: On the magnitude and frequency of Khurdopin glacier surge events

    OpenAIRE

    D. J. Quincey; Luckman, A.

    2014-01-01

    The return periods of Karakoram glacier surges are poorly quantified. Here, we present evidence of an historic surge of the Khurdopin Glacier that began in the mid-1970s and peaked in 1979. Measured surface displacements reached >5 km a−1, two orders of magnitude faster than during quiescence. The Khurdopin Glacier next surged in the late 1990s, equating to a return period of 20 years. Surge evolution in the two events shows remarkable similarity suggesting a common trigger....

  1. Furrow-irrigated chufa crops in Valencia (Spain. I: Productive response to two irrigation strategies

    Directory of Open Access Journals (Sweden)

    N. Pascual-Seva

    2013-01-01

    Full Text Available Chufa (Cyperus esculentus L. var. sativus Boeck. is an important vegetable crop in Valencia (Spain, where its tubers are used to produce a refreshing drink called 'horchata'. Water is relatively inexpensive, there are no data regarding the volumes of water used to grow chufa, and the irrigation water use efficiency (IWUE has neither been determined. The aim of this research was to compare the productive responses of the chufa crop to two irrigation strategies (IS. The volumetric soil water content (VSWC was monitored with capacitance sensors. Trends in VSWC were used to determine the in situ field capacity (FC, beginning each irrigation event when the VSWC reached either approximately 45% (H1 or 60% (H2 of the FC at a soil depth of 0.10 m. The experiments were conducted over three consecutive seasons. An area velocity flow module measured the water flow. The yields, the water volumes used, and the IWUE were calculated. Plants were periodically sampled and the harvest index and relative growth rate were determined. The yield was affected by the year and by the IS. The greatest yields were obtained with the H2 strategy (on average 2.18 kg m-2 for H2 vs. 1.94 kg m-2 for H1; p≤0.01, and the average tuber weight (ATW was affected (p≤0.01 by the year and IS interaction. IWUE was affected by the year, and none of the considered factors affected the harvest index (p≤0.05. It can be concluded that maintaining a higher VSWC would increase both yield and ATW without affecting IWUE.

  2. Expansion of an Existing Water Management Model for the Analysis of Opportunities and Impacts of Agricultural Irrigation under Climate Change Conditions

    Directory of Open Access Journals (Sweden)

    Jörg Steidl

    2015-11-01

    Full Text Available The impact of climate change and increased irrigation area on future hydrologic and agro-economic conditions was analysed for a representative basin in northeastern Germany using an expanded version of the WBalMO (water balance model for water management. The model expansion represents various temporally and spatially differentiated irrigation water use processes, including agricultural irrigation, as part of a river basin’s water management. We show that climate changes lead to increased irrigation water demands in the future, which will not always be able to be met. The resulting water deficits were shown for different crops depending on their irrigation priority and the water available. With an increased irrigation area, water deficits will rise. This may limit the profitability of agricultural irrigation. The impacts of climate change on low-flow conditions in the river are much higher than those of the increase in irrigated area alone. Therefore, any additional increases of irrigation will require careful monitoring of water availability to avoid critical impacts on river flows. The expanded model was able to replicate the processes of agricultural irrigation water use and can thus be used to test the impact of policies such as the certification of new irrigation permits.

  3. Influence of advective bio-irrigation on carbon and nitrogen cycling in sandy sediments

    OpenAIRE

    Na, T.; Gribsholt, B.; Galaktionov, O. S.; T. Lee; Meysman, F. J. R.

    2008-01-01

    In sandy sediments, the burrow ventilation activity of benthic macrofauna can generate substantial advective flows within the sediment surrounding their burrows. Here we investigated the effects of such advective bio-irrigation on carbon and nitrogen cycling in sandy sediments. To this end, we combined a range of complementary experimental and modelling approaches in a microcosm study of the lugworm Arenicola marina (Polychaeta: Annelida). Bio-irrigation rates were determined using uranine as...

  4. Influence of long-term sewage irrigation on the distribution of organochlorine pesticides in soil-groundwater systems.

    Science.gov (United States)

    Zhang, Caixiang; Liao, Xiaoping; Li, Jiale; Xu, Liang; Liu, Ming; Du, Bin; Wang, Yanxin

    2013-07-01

    Serious shortage of water resources is one of the major factors restricting the sustainable development of cropland and pasture land in northern and northwestern China. Although the reuse of wastewater for agricultural irrigation becomes a well established practice in these regions, many contaminants have been also introduced into the soil-groundwater systems such as persistent organochlorine pesticides (OCPs). To study the influence of long-term sewage irrigation on the distribution of OCPs in soil-groundwater systems, the groundwater flow field was investigated and 31 topsoil samples, 9 boreholes, 11 sewage effluents and 34 groundwater samples were collected in Xiaodian, Taiyuan city, one of the largest sewage irrigation districts, China. During sampling, three representative types of regions were considered including effluent-irrigated area, groundwater-irrigated area served as the control field and no-irrigated area as reference "background". The results showed over-exploitation of groundwater had changed the flow field of groundwater and wherever in soil or in groundwater, the concentration of OCPs in effluent-irrigation area presented the highest value, which indicated that the sewage irrigation had a strong influence on the distribution of OCPs in soil-groundwater systems. Principal component analysis for OCPs content in groundwater showed that the major influence factors on the occurrence and distribution of OCPs in groundwater systems attribute to the flow field of groundwater and to the current pesticide use.

  5. Evaluating the impact of irrigation on surface water – groundwater interaction and stream temperature in an agricultural watershed

    Science.gov (United States)

    Essaid, Hedeff I.; Caldwell, Rodney R.

    2017-01-01

    Changes in groundwater discharge to streams caused by irrigation practices can influence stream temperature. Observations along two currently flood-irrigated reaches in the 640-square-kilometer upper Smith River watershed, an important agricultural and recreational fishing area in west-central Montana, showed a downstream temperature decrease resulting from groundwater discharge to the stream. A watershed-scale coupled surface water and groundwater flow model was used to examine changes in streamflow, groundwater discharge to the stream and stream temperature resulting from irrigation practices. The upper Smith River watershed was used to develop the model framework including watershed climate, topography, hydrography, vegetation, soil properties and current irrigation practices. Model results were used to compare watershed streamflow, groundwater recharge, and groundwater discharge to the stream for three scenarios: natural, pre-irrigation conditions (PreIrr); current irrigation practices involving mainly stream diversion for flood and sprinkler irrigation (IrrCurrent); and a hypothetical scenario with only groundwater supplying sprinkler irrigation (IrrGW). Irrigation increased groundwater recharge relative to natural PreIrr conditions because not all applied water was removed by crop evapotranspiration. Groundwater storage and groundwater discharge to the stream increased relative to natural PreIrr conditions when the source of irrigation water was mainly stream diversion as in the IrrCurrent scenario. The hypothetical IrrGW scenario, in which groundwater withdrawals were the sole source of irrigation water, resulted in widespread lowering of the water table and associated decreases in groundwater storage and groundwater discharge to the stream. A mixing analysis using model predicted groundwater discharge along the reaches suggests that stream diversion and flood irrigation, represented in the IrrCurrent scenario, has led to cooling of stream temperatures

  6. 30 CFR 57.16002 - Bins, hoppers, silos, tanks, and surge piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Bins, hoppers, silos, tanks, and surge piles... NONMETAL MINES Materials Storage and Handling § 57.16002 Bins, hoppers, silos, tanks, and surge piles. (a) Bins, hoppers, silos, tanks, and surge piles, where loose unconsolidated materials are stored,...

  7. 30 CFR 56.16002 - Bins, hoppers, silos, tanks, and surge piles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Bins, hoppers, silos, tanks, and surge piles... MINES Materials Storage and Handling § 56.16002 Bins, hoppers, silos, tanks, and surge piles. (a) Bins, hoppers, silos, tanks, and surge piles, where loose unconsolidated materials are stored, handled...

  8. THE STUDY OF ALLOCATION OF SURGE BUNKER IN MINE HAULAGE SYSTEM

    Institute of Scientific and Technical Information of China (English)

    王喜富; 张幼蒂; 张达贤

    1997-01-01

    Based on the function analysis of surge bunker in mine haulage system, the authors raise the calculation methods of the total output of a mine haulage system. Taking the maximum of system's total throughput as a objective, the method of determining the surge bunker's rational size is put forward. Also, the problems of rational position of surge bunker are analysesed.

  9. A model study of Abrahamsenbreen, a surging glacier in northern Spitsbergen

    NARCIS (Netherlands)

    Oerlemans, J.; van Pelt, W. J. J.

    2015-01-01

    The climate sensitivity of Abrahamsenbreen, a 20 km long surge-type glacier in northern Spitsbergen, is studied with a simple glacier model. A scheme to describe the surges is included, which makes it possible to account for the effect of surges on the total mass budget of the glacier. A climate rec

  10. How to expand irrigated land in a sustainable way ?

    Science.gov (United States)

    Pastor, Amandine V.; Ludwig, Fulco; Palazzo, Amanda; Havlik, Petr; Kabat, Pavel

    2015-04-01

    Allocation of agriculture commodities and water resources is subject to changes due to climate change, population increase and changes in dietary patterns. This study focused on including global water availability including environmental flow requirements with water withdrawal from irrigation and other sectors (industry, household and hydropower) at a monthly time-step in the GLOBIOM model. This model allows re-adjustment of land-use allocation, crop management, consumption and international trade. The GLOBIOM model induces an endogenous change in water price depending on water supply and demand. In this study, the focus was on how the inclusion of water resources affects land-use and, in particular, how global change will influence repartition of irrigated and rainfed lands at global scale. We used the climate change scenario including a radiative forcing of 2.6 W/m2 (RCP2.6), the socio-economic scenario (SSP2: middle-of-road), and the environmental flow method based on monthly flow allocation (the Variable Monthly Flow method) with high and low restrictions. Irrigation withdrawals were adjusted to a monthly time-step to account for biophysical water limitations at finer time resolution. Our results show that irrigated land might decrease up to 37% on average depending on the choice of EFR restrictions. Several areas were identified as future hot-spots of water stress such as the Mediterranean and Middle-East regions and parts of South-East Asia where the Water Stress Indicator (WSI) ranges from 0.4 to 1 by 2050. Other countries were identified to be in safe position in terms of water stress such as North-European countries. Some countries such as India expect a significant increase in water demand which might be compensated by an increase in water supply with climate change scenario. Re-allocation of rainfed and irrigated land might be useful information for land-use planners and water managers at an international level to decide on appropriate legislations on

  11. Numerical model for surge and swab pressures on wells with cross-section variation

    Energy Technology Data Exchange (ETDEWEB)

    Fedevjcyk, Joao Victor; Junqueira, Silvio Luiz de Mello; Negrao, Cezar Otaviano Ribeiro [UTFPR - Federal University of Technology - Parana - Curitiba, PR (Brazil)], e-mails: silvio@utfpr.edu.br, negrao@utfpr.edu.br

    2010-07-01

    Drilling is one of the most complex steps in petroleum exploration. The process is accomplished by rotating a drill bit to compress the rock formation. During drilling, a fluid is pumped into the well to lubricate and cool down the drill bit, to clean up the well, to avoid the formation fluid influx to the well and also to stabilize the borehole walls. Fluid circulation, however, can be interrupted for maintenance reasons and the drill pipe can be moved to remove the drill bit. The downward or upward movement of the drill pipe displaces the fluid within the well causing either under pressure (swab) or over pressure (surge), respectively. If the pressure at the well bore overcomes the formation fracture pressure, a loss of circulation can take place. On the other way round, the upward movement may reduce the pressure below the pore pressure and an inflow of fluid to the well (kick) can occur. An uncontrolled kick may cause a blowout with serious damages. The transient flow induced by the axial movement of the drill pipe is responsible for the pressure changes at the well bore. Nevertheless, the well bore cross section variation may modify the pressure change within the pipe. In this paper, the effects of diameter variation of the drilling well on the surge and swab pressures are investigated. The equations that represent the phenomenon (mass and momentum conservation) are discretized by the finite volume method. Despite its non-Newtonian properties, the fluid is considered Newtonian in this first work. The drill pipe is considered closed and the flow is assumed as single-phased, one-dimensional, isothermal, laminar, compressible and transient. A sensitivity analysis of the flow parameters is carried out. The cross-section changes cause the reflection of the pressure wave, and consequently pressure oscillations. (author)

  12. Sediment transport in irrigation canals.

    NARCIS (Netherlands)

    Mendez V., N.J.

    1998-01-01

    The world population is rapidly increasing and is expected to double to about 10 billion by the year 2050. To support an increasing population in terms of food sufficiency, more and more water will be required. Irrigation is the most critical component of the modern package of inputs to effect high

  13. Sediment transport in irrigation canals

    NARCIS (Netherlands)

    Mendez V., N.J.

    1998-01-01

    The world population is rapidly increasing and is expected to double to about 10 billion by the year 2050. To support an increasing population in terms of food sufficiency, more and more water will be required. Irrigation is the most critical component of the modern package of inputs to

  14. Position paper : Whole bowel irrigation

    NARCIS (Netherlands)

    2004-01-01

    Whole bowel irrigation (WBI) should not be used routinely in the management of the poisoned patient. Although some volunteer studies have shown substantial decreases in the bioavailability of ingested drugs, no controlled clinical trials have been performed and there is no conclusive evidence that W

  15. Use of an Irrigation Pump System in Arthroscopic Procedures.

    Science.gov (United States)

    Hsiao, Mark S; Kusnezov, Nicholas; Sieg, Ryan N; Owens, Brett D; Herzog, Joshua P

    2016-05-01

    Since its inception, arthroscopic surgery has become widely adopted among orthopedic surgeons. It is therefore important to have an understanding of the basic principles of arthroscopy. Compared with open techniques, arthroscopic procedures are associated with smaller incisions, less structural damage, improved intra-articular visualization, less pain in the immediate postoperative period, and faster recovery for patients. Pump systems used for arthroscopic surgery have evolved over the years to provide improved intraoperative visualization. Gravity flow systems were described first and are still commonly used today. More recently, automated pump systems with pressure or dual pressure and volume control have been developed. The advantages of automated irrigation systems over gravity irrigation include a more consistent flow, a greater degree of joint distention, improved visualization especially with motorized instrumentation, decreased need for tourniquet use, a tamponade effect on bleeding, and decreased operative time. Disadvantages include the need for additional equipment with increased cost and maintenance, the initial learning curve for the surgical team, and increased risk of extra-articular fluid dissection and associated complications such as compartment syndrome. As image quality and pump systems improve, so does the list of indications including diagnostic and treatment modalities to address intra-articular pathology of the knee, shoulder, hip, wrist, elbow, and ankle joints. This article reviews the current literature and presents the history of arthroscopy, basic science of pressure and flow, types of irrigation pumps and their functions, settings, applications, and complications. [Orthopedics. 2016; 39(3):e474-e478.].

  16. Building and Analyzing SURGEDAT: The World's Most Comprehensive Storm Surge Database

    Science.gov (United States)

    Needham, H.; Keim, B.

    2012-12-01

    SURGEDAT, the world's most comprehensive tropical storm surge database, has identified and mapped the location and height of hundreds of global storm surge events. This project originated with a study that identified more than 200 tropical surge events along the U.S. Gulf Coast. Spatial analysis of these data reveal that the central and western Gulf Coast observe more frequent and higher magnitude surges, whereas much of the eastern Gulf Coast, including the west coast of Florida, experiences less storm surge activity. Basin-wide return period analysis of these data estimate a 100-year return period of 8.20m, and a 10-year return period of 4.95m. Return period analysis of 10 sub-regions within the basin reveal that the highest surge levels occur in the Southeast Louisiana/ Mississippi zone, which includes the New Orleans metropolitan area. The 100-year surge level in this zone is estimated to be 7.67m. The Southeast Texas/ Southwest Louisiana zone, which includes the Houston metropolitan area, has the second highest surge levels, with a 100-year storm surge estimate of 6.30m. Surge levels are lower on the west coast of Florida, where the 100-year surge level is estimated between three and four meters. Expansion of this work includes mapping all high water marks for each surge event and the creation of a search-by-location web tool, which enables users to see the entire storm surge history for specific locations. In addition, the dataset has expanded internationally and now includes more than 500 surge events, as surges have now been identified in all the major ocean basins that experience tropical cyclones. International partnerships are sought to further expand this work, particularly in Australia, China, Japan, Philippines, India, Bangladesh, Myanmar, Mexico and various countries in Oceania and the Caribbean.; ;

  17. Effect of infiltration modeling approach on operational solutions for furrow irrigation

    Science.gov (United States)

    Infiltration in irrigated furrows depends on the variation of depth of flow and, thus, wetted perimeter along the field and in time. However, the magnitude of the wetted perimeter effect has not been clearly established due to soil variability, erosion and deposition, macropore flow, and other proc...

  18. Analysis on Lightning Surge Propagation in Wind Farm

    Science.gov (United States)

    Yasuda, Yoh; Hara, Takehisa; Funabashi, Toshihisa

    Wind power generation is expected to become more important in the future distribution system. Although several prospective reports such as IEC 61400-24 and NREL SR-500-31115 indicate on insulation scheme and grounding design for lightning protection, it still seems that there are not many investigations on the problems. This paper therefore discusses lightning surge analysis using wind farm model with 2 or 10 ideal wind turbines. Changing parameters such as grounding resistance and lightning strike points, several cases were studied. As the result of the analysis using digital simulator ARENE, it is clear that the surge tends to propagate toward the end of a distribution line in a wind farm and there is possibility of insulation accidents at the other wind turbines when lightning attacks a wind turbine.

  19. RESEARCH ON THE CONDITION TO SET A TAILRACE SURGE TANK

    Institute of Scientific and Technical Information of China (English)

    ZHAO Gui-lian; YANG jian-dong; XU Yuan-jie; LI Jin-ping

    2004-01-01

    When using the draft-tube vacuum to be less than 8.0m as the rule to set a tailrace surge tank, a mixing function that describes the process of water-hammer vacuum and velocity-head vacuum varied with time is proposed, on the assumption that the guide vane of the hydraulic turbine and the turbine discharge were all changed linearly. An exact maximum of the draft-tube vacuum for the first-phase water-hammer and the last-phase water-hammer is obtained. Finally a much more reasonable formula of critical tailrace length is derived. The results of two cases show that the formula proposed can determine correctly and reasonably whether a tailrace surge tank is needed or not, and are more suitable for project design than the formula suggested by the specification.

  20. Use of historical information in extreme storm surges frequency analysis

    Science.gov (United States)

    Hamdi, Yasser; Duluc, Claire-Marie; Deville, Yves; Bardet, Lise; Rebour, Vincent

    2013-04-01

    The prevention of storm surge flood risks is critical for protection and design of coastal facilities to very low probabilities of failure. The effective protection requires the use of a statistical analysis approach having a solid theoretical motivation. Relating extreme storm surges to their frequency of occurrence using probability distributions has been a common issue since 1950s. The engineer needs to determine the storm surge of a given return period, i.e., the storm surge quantile or design storm surge. Traditional methods for determining such a quantile have been generally based on data from the systematic record alone. However, the statistical extrapolation, to estimate storm surges corresponding to high return periods, is seriously contaminated by sampling and model uncertainty if data are available for a relatively limited period. This has motivated the development of approaches to enlarge the sample extreme values beyond the systematic period. The nonsystematic data occurred before the systematic period is called historical information. During the last three decades, the value of using historical information as a nonsystematic data in frequency analysis has been recognized by several authors. The basic hypothesis in statistical modeling of historical information is that a perception threshold exists and that during a giving historical period preceding the period of tide gauging, all exceedances of this threshold have been recorded. Historical information prior to the systematic records may arise from high-sea water marks left by extreme surges on the coastal areas. It can also be retrieved from archives, old books, earliest newspapers, damage reports, unpublished written records and interviews with local residents. A plotting position formula, to compute empirical probabilities based on systematic and historical data, is used in this communication paper. The objective of the present work is to examine the potential gain in estimation accuracy with the

  1. Rapid Response Measurements of Hurricane Waves and Storm Surge

    Science.gov (United States)

    Gravois, U.

    2010-12-01

    Andrew (1992), Katrina (2005), and Ike (2008) are recent examples of extensive damage that resulted from direct hurricane landfall. Some of the worst damages from these hurricanes are caused by wind driven waves and storm surge flooding. The potential for more hurricane disasters like these continues to increase as a result of population growth and real estate development in low elevation coastal regions. Observational measurements of hurricane waves and storm surge play an important role in future mitigation efforts, yet permanent wave buoy moorings and tide stations are more sparse than desired. This research has developed a rapid response method using helicopters to install temporary wave and surge gauges ahead of hurricane landfall. These temporary installations, with target depths from 10-15 m and 1-7 km offshore depending on the local shelf slope, increase the density of measurement points where the worst conditions are expected. The method has progressed to an operational state and has successfully responded to storms Ernesto (2006), Noel (2007), Fay (2008), Gustav (2008), Hanna (2008) and Ike (2008). The temporary gauges are pressure data loggers that measure at 1 Hz continuously for 12 days and are post-processed to extract surge and wave information. For the six storms studied, 45 out of 49 sensors were recovered by boat led scuba diver search teams, with 43 providing useful data for an 88 percent success rate. As part of the 20 sensor Hurricane Gustav response, sensors were also deployed in lakes and bays inLouisiana, east of the Mississippi river delta. Gustav was the largest deployment to date. Generally efforts were scaled back for storms that were not anticipated to be highly destructive. For example, the cumulative total of sensors deployed for Ernesto, Noel, Fay and Hanna was only 20. Measurement locations for Gustav spanned over 800 km of exposed coastline from Louisiana to Florida with sensors in close proximity to landfall near Cocodrie

  2. Source of a Prominent Poleward Surge During Solar Cycle 24

    CERN Document Server

    Yeates, A R; van Driel-Gesztelyi, L

    2015-01-01

    As an observational case study, we consider the origin of a prominent poleward surge of leading polarity, visible in the magnetic butterfly diagram during Solar Cycle 24. A new technique is developed for assimilating individual regions of strong magnetic flux into a surface flux transport model. By isolating the contribution of each of these regions, the model shows the surge to originate primarily in a single high-latitude activity group consisting of a bipolar active region present in Carrington Rotations 2104-05 (November 2010-January 2011) and a multipolar active region in Rotations 2107-08 (February-April 2011). This group had a strong axial dipole moment opposed to Joy's law. On the other hand, the modelling suggests that the transient influence of this group on the butterfly diagram will not be matched by a large long-term contribution to the polar field, because of its location at high latitude. This is in accordance with previous flux transport models.

  3. A Fuzzy Control Irrigation System For Cottonfield

    Science.gov (United States)

    Zhang, Jun; Zhao, Yandong; Wang, Yiming; Li, Jinping

    A fuzzy control irrigation system for cotton field is presented in this paper. The system is composed of host computer, slave computer controller, communication module, soil water sensors, valve controllers, and system software. A fuzzy control model is constructed to control the irrigation time and irrigation quantity for cotton filed. According to the water-required rules of different cotton growing periods, different irrigation strategies can be carried out automatically. This system had been used for precision irrigation of the cotton field in Langfang experimental farm of Soil and Fertilizer Institute, Chinese Academy of Agricultural Sciences in 2006. The results show that the fuzzy control irrigation system can improve cotton yield and save much water quantity than the irrigation system based on simple on-off control algorithm.

  4. Controlling near shore nonlinear surging waves through bottom boundary conditions

    CERN Document Server

    Mukherjee, Abhik; Kundu, Anjan

    2016-01-01

    Instead of taking the usual passive view for warning of near shore surging waves including extreme waves like tsunamis, we aim to study the possibility of intervening and controlling nonlinear surface waves through the feedback boundary effect at the bottom. It has been shown through analytic result that the controlled leakage at the bottom may regulate the surface solitary wave amplitude opposing the hazardous variable depth effect. The theoretical results are applied to a real coastal bathymetry in India.

  5. Wildlife Poaching: Africa’s Surging Trafficking Threat

    Science.gov (United States)

    2014-05-01

    called keratin, an inert substance that is similar in composition to human fingernails and hair. Some of the consequences of wildlife trafficking are...of the few central figures to have been convicted is a Thai trafficker named Chumlong Lem- tongthai, who worked for businesses in Thailand and Laos...4 1 Wildlife Poaching: Africa’s Surging Trafficking Threat By Bradley anderson and Johan Jooste u Spikes in the prices of ivory and rhino horn have

  6. Enkephalin surges in dorsal neostriatum as a signal to eat

    OpenAIRE

    DiFeliceantonio, Alexandra G.; Mabrouk, Omar S.; Kennedy, Robert T.; C. Berridge, Kent

    2012-01-01

    Compulsive over-consumption of rewards characterizes disorders ranging from binge eating to drug addiction. Here, we provide evidence that enkephalin surges in an anteromedial quadrant of dorsal neostriatum contribute to generating intense consumption of palatable food. In ventral striatum, mu opioid circuitry contributes an important component of motivation to consume rewards [1–4]. In dorsal neostriatum, mu opioid receptors are concentrated within striosomes that receive inputs from limbic ...

  7. Population vulnerability to storm surge flooding in coastal Virginia, USA.

    Science.gov (United States)

    Liu, Hua; Behr, Joshua G; Diaz, Rafael

    2016-07-01

    This study aims to assess the vulnerability of populations to storm surge flooding in 12 coastal localities of Virginia, USA. Population vulnerability is assessed by way of 3 physical factors (elevation, slope, and storm surge category), 3 built-up components (road availability, access to hospitals, and access to shelters), and 3 household conditions (storm preparedness, financial constraints to recovering from severe weather events, and health fragility). Fuzzy analysis is used to generate maps illustrating variation in several types of population vulnerability across the region. When considering physical factors and household conditions, the most vulnerable neighborhoods to sea level rise and storm surge flooding are largely found in urban areas. However, when considering access to critical infrastructure, we find rural residents to be more vulnerable than nonrural residents. These detailed assessments can inform both local and state governments in catastrophic planning. In addition, the methodology may be generalized to assess vulnerability in other coastal corridors and communities. The originality is highlighted by evaluating socioeconomic conditions at refined scale, incorporating a broader range of human perceptions and predispositions, and employing a geoinformatics approach combining physical, built-up, and socioeconomic conditions for population vulnerability assessment. Integr Environ Assess Manag 2016;12:500-509. © 2015 SETAC. © 2015 SETAC.

  8. Mass balance, runoff and surges of Bering Glacier, Alaska

    Directory of Open Access Journals (Sweden)

    W. Tangborn

    2013-05-01

    Full Text Available The historical net, ablation and accumulation daily balances, as well as runoff of Bering Glacier, Alaska are determined for the 1951–2011 period with the PTAA (precipitation-temperature-area-altitude model, using daily precipitation and temperature observations collected at the Cordova and Yakutat weather stations, together with the area-altitude distribution of the glacier. The model mean annual balance for this 61 yr period is −0.6 m w.e., the accumulation balance is +1.4 and the ablation balance is −2.0 m w.e. Average annual runoff is 2.5 m w.e. Periodic surges of this glacier transport large volumes of ice to lower elevations where the ablation rate is higher, producing more negative balances and increasing runoff. Runoff from Bering Glacier (derived from simulated ablation and precipitation as rain is highly correlated with four of the glacier surges that have occurred since 1951. Ice volume loss for the 1972–2003 period measured with the PTAA model is 2.7 km3 w.e. a−1 and closely agrees with losses for the same period measured with the geodetic method. It is proposed that the timing and magnitude of daily snow accumulation and runoff, both of which are controlled by the glacier's area-altitude distribution and are calculated with the PTAA model, can be used to determine the probability that a glacier will surge.

  9. Hospitals Capability in Response to Disasters Considering Surge Capacity Approach

    Directory of Open Access Journals (Sweden)

    Gholamreza Khademipour

    2016-01-01

    Full Text Available Background: The man-made and natural disasters have adverse effects with sound, apparent, and unknown consequences. Among various components of disaster management in health sector, the most important role is performed by health-treatment systems, especially hospitals. Therefore, the present study aimed to evaluate the surge capacity of hospitals of Kerman Province in disaster in 2015. Materials and Methods: This is a quantitative study, conducted on private, military, and medical sciences hospitals of Kerman Province. The sampling method was total count and data collection for the research was done by questionnaire. The first section of the questionnaire included demographic information of the studied hospitals and second part examined the hospital capacity in response to disasters in 4 fields of equipment, physical space, human resources, and applied programs. The extracted data were analyzed by descriptive statistics. Results: The mean capability of implementing the surge capacity programs by hospitals of Kerman Province in disasters and in 4 fields of equipment, physical space, human resources, and applied programs was evaluated as 7.33% (weak. The surge capacity capability of state hospitals in disasters was computed as 8% and compared to private hospitals (6.07% had a more suitable condition. Conclusion: Based on the results of study and significance of preparedness of hospitals in response to disasters, it is proposed that managers of studied hospitals take measures to promote the hospital response capacity to disasters based on 4 components of increasing hospital capacity.

  10. Using satellite altimetry and tide gauges for storm surge warning

    Science.gov (United States)

    Andersen, O. B.; Cheng, Y.; Deng, X.; Steward, M.; Gharineiat, Z.

    2015-03-01

    The combination of the coarse temporal sampling by satellite altimeters in the deep ocean with the high temporal sampling at sparsely located tide gauges along the coast has been used to improve the forecast of high water for the North Sea along the Danish Coast and for the northeast coast of Australia. For both locations we have tried to investigate the possibilities and limitations of the use of satellite altimetry to capture high frequency signals (surges) using data from the past 20 years. The two regions are chosen to represent extra-tropical and tropical storm surge conditions. We have selected several representative high water events on the two continents based on tide gauge recordings and investigated the capability of satellite altimetry to capture these events in the sea surface height data. Due to the lack of recent surges in the North Sea we focused on general high water level and found that in the presence of two or more satellites we could capture more than 90% of the high water sea level events. In the Great Barrier Reef section of the northeast Australian coast, we have investigated several large tropical cyclones; one of these being Cyclone Larry, which hit the Queensland coast in March 2006 and caused both loss of lives as well as huge devastation. Here we demonstrate the importance of integrating tide gauges with satellite altimetry for forecasting high water at the city of Townsville in northeast Australia.

  11. Mass balance, runoff and surges of the Bering Glacier, Alaska

    Directory of Open Access Journals (Sweden)

    W. Tangborn

    2012-12-01

    Full Text Available The historical net, ablation and accumulation daily balances and runoff of the Bering Glacier, Alaska are determined for the 1951–2011 period with the PTAA (precipitation-temperature-area-altitude model, using daily precipitation and temperature observations collected at the Cordova and Yakutat weather stations, together with the area-altitude distribution of the glacier. The mean annual balance for this 61-yr period is −0.6 mwe, the accumulation balance is +1.4 and the ablation balance is −2.0 mwe. Periodic surges of this glacier transport large volumes of ice to lower elevations where the ablation rate is higher, producing more negative balances and increasing runoff. During the 1993–1995 surge the average ablation balance is −3.3 mwe, over a meter greater than the 1951–2011 average. Runoff from the Bering Glacier (derived from simulated ablation and precipitation as rain is highly correlated with the four glacier surges that have been observed since 1951. Ice volume loss for the 1972–2003 period measured with the PTAA model is 2.3 km3 we a−1 and closely agrees with losses for the same period measured with the geodetic method.

  12. H{α} Surges Aroused by Newly-emerging Satellite Bipolar Magnetic Field

    Science.gov (United States)

    Wang, J. F.; Zhou, T. H.; Ji, H. S.

    2013-07-01

    An Hα surge event occurred at AR NOAA 11259 on 2011 July 22. According to the BBSO (Big Bear Solar Observatory) Hα line-center observations, three surges continuously ejected from the same region to the north of the main-sunspot of AR 11259. All of surges ejected along a straight trajectory, and looked like the reversed Eiffel Tower. The first and second surges had the same process. Two bright points firstly appeared to the north of the main-sunspot. After several minutes, a surge appeared between the two bright points, and then rapidly ejected when the two points got most brightness.When the surge reached the maximum height, it disappeared quickly. However, the third surge appeared without bright points, and its height was only half of the others. Compared with SDO/HMI (Solar Dynamics Observatory/Helioseismic and Magnetic Imager) line-of-sight magnetogram, more than one hour before the first surge appeared, a satellite bipolar magnetic field emerged from the surge-ejection region. The newly-emerging positive magnetic flux showed a distinct decrease several minutes earlier than the ejection of the surges. We assumed that the surges was associated with the reconnection between the newly-emerging bipolar magnetic field and the existing (sunspot) magnetic field.

  13. Can we use crevasse fill ridges for identifying undocumented surge behavior in Svalbard?

    Science.gov (United States)

    Farnsworth, W. R.; Ingolfsson, O.; Schomacker, A.; Retelle, M.

    2015-12-01

    Documenting glaciers that exhibit surge type behavior is crucial, especially as we attempt to use evidence of ice front fluctuations for reconstructing past climate oscillations. Controversy exists regarding the relationship between surge activity and climatic processes such as mass balance. This project identifies undocumented surge type glaciers in Svalbard based on the presence of crevasse fill ridges (CFRs) visible in glacier forelands. Although it is acknowledged that many Svalbard outlet glaciers surge, estimates vary greatly as to the actual number of surge- type glaciers in Svalbard, and their distribution pattern is not well understood. A detailed survey of recent (2008-2011), high resolution imagery from Toposvalbard, provided by the Norwegian Polar Institute, allowed for a rapid analysis of Svalbard outlet glaciers. Using CFRs as indicators of surge behavior has almost doubled the amount of potential surge-type glaciers in central Spitsbergen. This method also highlights numerous other glaciers of potential surge type behavior throughout the archipelago. Limits to the CFR identification method are discussed. Additionally as the forelands of previously reported surge type glaciers were analyzed for CFRs, it was evident that the surge indicators were only present in approximately half of the forelands. Numerous factors control the formation and preservation of CFRs including; glacier size, bedrock lithology, subglacial sediments and clast size as well as glacial fluvial run-off. This poster focuses on the controlling factors for CFR formation and preservation as well as other potential methods for effectively identifying surge behavior.

  14. Response to the sudden closure of St. Vincent's Hospital: learning from a real, no-notice, prolonged surge event.

    Science.gov (United States)

    Adalja, Amesh A; Watson, Matthew; Wollner, Samuel; Rambhia, Kunal J; Toner, Eric S

    2011-06-01

    We qualitatively examined the impact of the permanent closure of St. Vincent's Hospital in New York City on the remaining hospitals in the area and analyzed how these hospitals responded to this event. We conducted a descriptive survey consisting of interviews with clinical (n = 24) and administrative (n = 11) staff from 4 hospitals in lower Manhattan after the sudden closure of St. Vincent's Hospital. These hospitals experienced a sudden and sustained increase in patient volume. Each was faced with specific constraints (eg, finances, physical plant, bureaucracy), but they developed similar strategic responses. Generally applicable principles included: soliciting innovative ideas from clinical staff, reexamining previous proposals to improve efficiency, fast-tracking stalled capacity-building projects, and focusing on improving patient care and flow. Three broad tactical themes were apparent: increases in staff and staff hours, use of alternative sites of care, and implementing novel ways of operating. The impact on hospital operations resulting from the closure of St. Vincent's Hospital is a surrogate medical surge event and met thresholds for activating emergency operations plans. Novel operating methods used in response to this surge event offer practical and broadly applicable principles that might improve medical surge management in other hospitals.

  15. Assessing soil water storage distribution under sprinkler irrigation by coupling 3D simulations and field observations

    Science.gov (United States)

    Taha, Uday; Shabeeb, Ahmed; dragonetti, giovanna; Lamaddalena, Nicola; Coppola, Antonio

    2016-04-01

    This work analyzed the variability of sprinkler irrigation application over a bare soil, both in terms of water application efficiency and uniformity, by integrating and comparing the information on the irrigation depth data (ID), as measured by catch cans, soil water storage in the upper root zone, as measured by TDR probes, and a 3D simulations of water flow in soils. Three irrigation tests were performed at three different pressures (2, 3 and 4 bar). A lateral water redistribution was observed and simulated after each irrigation event by comparing spatial distributions of site-specific water application efficiency (AEs), as well as ratios of site-specific actual water storage increase (SWEs) and irrigation depth (IDs) to the water content before irrigation. Because of soil water redistribution processes, distribution uniformity based on soil storages was systematically higher than the catch can uniformity. The obvious consequence of lateral water redistribution processes was that the soil smoothing action on non-uniformity observed at the surface increased both with depth and over time. At a given depth the uniformity of soil water storages always attained the same value, whatever the pressure considered and the catch can-based uniformity coefficient. It was concluded that, for the case of random distribution of ID, the uniformity of water storages is driven by the soil behavior rather than by the irrigation system.

  16. Efficacy of nasal irrigation in the treatment of acute sinusitis in atopic children.

    Science.gov (United States)

    Wang, Yun-Hu; Ku, Min-Sho; Sun, Hai-Lun; Lue, Ko-Huang

    2014-02-01

    Nasal irrigation has been used as adjunctive therapy for sinonasal disease but is under-researched in children. The study aim was to evaluate the effectiveness of nasal irrigation with normal saline in the management of acute sinusitis in atopic children. We enrolled 60 atopic children with acute sinusitis, of whom 29 received nasal irrigation with normal saline and 31 did not receive nasal irrigation. All participants underwent a nasal peak expiratory flow rate (nPEFR) test, a nasal smear examination, and radiography (Water's projection) and were requested to complete a Pediatric Rhinoconjunctivitis Quality-of-Life Questionnaire (PRQLQ) during the baseline visit. All participants were requested to record symptoms in a daily diary and were followed up at 1-week intervals. A physical examination, nasal smear, and nPEFR were performed at each visit, and all daily diaries were collected. At the final visit (after 3 weeks), the symptom diaries were reviewed and participants were requested to complete the PRQLQ again. nPEFR, radiography, and a nasal smear were also repeated. There were significant improvements in mean PRQLQ and nPEFR values (p 0.05). The irrigation group recorded significant improvements in eye congestion, rhinorrhea, nasal itching, sneezing, and cough symptoms compared with the non-irrigation group. Nasal irrigation is an effective adjunctive treatment for acute sinusitis in atopic children. Copyright © 2012. Published by Elsevier B.V.

  17. Distribution of the root system of peach palm under drip irrigation

    Directory of Open Access Journals (Sweden)

    Adriano da Silva Lopes

    2014-07-01

    Full Text Available The incorporation of technologies has resulted in increased productivity and the more rational management of peach palm, with irrigation being an important tool for certain regions. Thus, studies leading to proper crop management are extremely important, such as the estimate of the effective depth of the root system, which is indispensable for proper irrigation management. The objective of this study was to evaluate the effects of different irrigation depths, as applied by drip irrigation, on the distribution of the root system of peach palm. This experiment was conducted in Ilha Solteira, São Paulo State, Brazil, with drip irrigation, with the two systems (flow of 0.0023 m3 h-1 consisting of four irrigation treatments corresponding to 0, 50, 100 and 150% of Class ‘A’ pan evaporation. After five years, an analysis of the Bactris gasipaes root system was performed at a distance of 0.0, 0.5 and 1.0 meters from the trunk, collecting sampling at two depths (0.0 to 0.3 m and 0.3 to 0.6 m via the auger method (volumetric analysis. We concluded that the effective depth of the root system used for irrigation management should be a maximum of 0.3 meters.

  18. Technical Evaluation of Sprinkler Irrigation Systems which were Implemented in Tea Fields of the Guilan Province

    Directory of Open Access Journals (Sweden)

    kourosh majdsalimi

    2016-02-01

    measuring pressure fluctuations which were applied to the entire system. Using irrigated area and irrigation water depth, adequacy of irrigation curve, deep percolation losses and spray losses were determined on the basis of existing relationships. Results and Discussion: Average values of CU, DU, PELQ and AELQ for 6 tea fields were 65, 52, 44 and 44 percent, respectively. Application efficiency in all irrigation systems, Christiansen’s uniformity coefficient and distribution uniformity were lower than recommended values in the references. Merriam and Keller (11 reported the allowable range for potential application efficiency of low-quarter between 65 to 85 percent. With respect to irrigation less than the actual water requirement of the plant in tea fields, AELQ was equal with PELQ. Untechnical design and implementation of irrigation systems, particularly poor operating pressure and economic problems were detected as the main reasons for the low PELQ. Simultaneous use of sprinklers with different specifications and models, old irrigation systems, water leakage from valves and other equipment, practically change the pressure and flow rate, which were the main reasons for the decrease in uniformity of water distribution and application efficiency of low-quarter. According to Cobban (4 uniformity coefficient of sprinkler irrigation systems were reported between 31 to 55 percent in Tanzania tea fields and in other reports were between 58 to 72 percent (7, which was due to poor design, long spacing of sprinklers and high speed wind. Christiansen’s uniformity coefficient and distribution uniformity of low-quarter in ED, WB & EP systems were lower than recommended values by Merriam and Keller (%81≥CU≥87% & %67≥DU≥80%(10. In spite of the little losses in deep percolation, irrigation adequacy of these systems was relatively low and unacceptable. In such circumstances, only about 20 to 38% of irrigated area in WA and CK systems, respectively received the required water

  19. Coupled modeling of storm surge and coastal inundation: A case study in New York City during Hurricane Sandy

    Science.gov (United States)

    Yin, Jie; Lin, Ning; Yu, Dapeng

    2016-11-01

    In this paper, we describe a new method of modeling coastal inundation arising from storm surge by coupling a widely used storm surge model (ADCIRC) and an urban flood inundation model (FloodMap). This is the first time the coupling of such models is implemented and tested using real events. The method offers a flexible and efficient procedure for applying detailed ADCIRC storm surge modeling results along the coastal boundary (with typical resolution of ˜100 m) to FloodMap for fine resolution inundation modeling (Hurricane Sandy was simulated at both the city (New York City) and subregional (lower Manhattan) scales with various resolutions. Results obtained from the ADCIRC and coupled ADCIRC-FloodMap simulations were compared with the recorded (high water marks) and derived (inundation extent based on the planar method) data from FEMA. At the city scale, coupled ADCIRC-FloodMap modeling demonstrates improved prediction over ADCIRC modeling alone for both the extent and depth of inundation. The advantage of the coupled model is further illustrated in the subregional modeling, using a mesh resolution of 3 m which is substantially finer than the inland mesh resolution used by ADCIRC (>70 m). In further testing, we explored the effects of mesh resolution and roughness specification. Results agree with previous studies that fine resolution is essential for capturing intricate flow paths and connectivity in urban topography. While the specification of roughness is more challenging for urban environments, it may be empirically optimized. The successful coupling of ADCIRC and FloodMap models for fine resolution coastal inundation modeling unlocks the potential for undertaking large numbers of probabilistically based synthetic surge events for street-level risk analysis.

  20. Base surge deposits, eruption history, and depositional processes of a wet phreatomagmatic volcano in Central Anatolia (Cora Maar)

    Science.gov (United States)

    Gençalioğlu-Kuşcu, Gonca; Atilla, Cüneyt; Cas, Ray A. F.; Kuşcu, İlkay

    2007-01-01

    Cora Maar is a Quaternary volcano located to the 20 km northwest of Mount Erciyes, the largest of the 19 polygenetic volcanic complexes of the Cappadocian Volcanic Province in central Anatolia. Cora Maar is a typical example of a maar-diatreme volcano with a nearly circular crater with a mean diameter of c.1.2 km, and a well-bedded base surge-dominated maar rim tephra sequence up to 40 m in thickness. Having a diameter/depth ratio ( D/ d) of 12, Cora is a relatively "mature" maar compared to recent maar craters in the world. Cora crater is excavated within the andesitic lava flows of Quaternary age. The tephra sequence is not indurated, and consists of juvenile clasts up to 70 cm, non-juvenile clasts up to 130 cm, accretionary lapilli up to 1.2 cm in diameter, and ash to lapilli-sized tephra. Base surge layers display well-developed antidune structures indicating the direction of the transport. Both progressive and regressive dune structures are present within the tephra sequence. Wavelength values increase with increasing wave height, and with large wavelength and height values. Cora tephra display similarities to Taal and Laacher See base surge deposits. Impact sags and small channel structures are also common. Lateral and vertical facies changes are observed for the dune bedded and planar bedsets. According to granulometric analyses, Cora Maar tephra samples display a bimodal distribution with a wide range of Md φ values, characteristic for the surge deposits. Very poorly sorted, bimodal ash deposits generally vary from coarse tail to fine tail grading depending on the grain size distribution while very poorly sorted lapilli and block-rich deposits display a positive skewness due to fine tail grading.

  1. Monitoring of surge tanks in hydroelectric power plants using fuzzy control; Ueberwachung von Wasserschloessern in Wasserkraftwerken mit Fuzzy-Control

    Energy Technology Data Exchange (ETDEWEB)

    Lin, J.C.

    2000-07-01

    Surge tanks are used to reduce pressure variations caused by fluid transients in high-head hydroelectric power plants. Occasionally load increases have to be limited to prevent the surge tank from draining due to excessive demands of flow. A control concept based on fuzzy logic was developed for governing the load changes of hydroelectric power plants. In order to achieve an optimal control behaviour and simultaneously to avoid the draining of surge tanks, the speed of load increases is automatically adjusted by a fuzzy conclusion depending on the height and the gradient of the water level in the surge tank, the reservoir level and the sum of load increases. The hydroelectric power plant Achensee of Tiroler Wasserkraftwerke AG in Austria is taken as an example to demonstrate the characteristics of the control concept. In comparison with a conventional control concept, the operation of load increases using the fuzzy concept proves to be more flexible and unrestricted. (orig.) [German] Ein Wasserschloss dient zur Verminderung von Druckschwankungen im Wasserfuehrungssystem von Hochdruckanlagen. Gelegentlich muss man die Lastaufnahme so beschraenken, dass das Wasserschloss nicht durch uebermaessige Wasserentnahme leerlaeuft. Fuer die Leistungsregelung eines Wasserkraftwerks wurde ein Konzept entwickelt, das auf der Fuzzy-Control in Verbindung mit der klassischen Regelung beruht. Um ein optimales Regelverhalten zu erhalten und gleichzeitig das Leerlaufen des Wasserschlosses zu vermeiden, wird die Geschwindigkeit der Lastaufnahme in Abhaengigkeit von der Hoehenkote und dem Gradienten des Wasserschlosspegels, dem Pegel des Oberwassers und der Groesse der geforderten Lasterhoehung automatisch eingestellt. Die Untersuchung erfolgt am Beispiel des Achenseekraftwerkes der Tiroler Wasserkraftwerke AG, Oesterreich. Im Vergleich mit einer konventionellen Regelung ergibt sich mit dem Fuzzy-Konzept eine flexiblere und freizuegigere Lastaufnahme. (orig.)

  2. Simulation hydraulique d'une rampe de micro-irrigation par la méthode dite " des volumes de contrôle "

    OpenAIRE

    Zella, Lakhdar; Kettab, Ahmed; Chassériaux, Gérard

    2003-01-01

    International audience; Hydraulic simulation of micro-irrigation lateral using control volume method. The optimization of the uniformity of water distribution by emitters determines the efficiency factor of the micro-irrigation network. Model simulation enables the research of the characteristics of a micro-irrigation network in order to optimise the water distribution uniformity at a reasonable investment cost. The variation of flow among emitters along the lateral is due to the variation of...

  3. Present-day irrigation mitigates heat extremes

    Science.gov (United States)

    Thiery, Wim; Davin, Edouard L.; Lawrence, David M.; Hirsch, Annette L.; Hauser, Mathias; Seneviratne, Sonia I.

    2017-02-01

    Irrigation is an essential practice for sustaining global food production and many regional economies. Emerging scientific evidence indicates that irrigation substantially affects mean climate conditions in different regions of the world. Yet how this practice influences climate extremes is currently unknown. Here we use ensemble simulations with the Community Earth System Model to assess the impacts of irrigation on climate extremes. An evaluation of the model performance reveals that irrigation has a small yet overall beneficial effect on the representation of present-day near-surface climate. While the influence of irrigation on annual mean temperatures is limited, we find a large impact on temperature extremes, with a particularly strong cooling during the hottest day of the year (-0.78 K averaged over irrigated land). The strong influence on extremes stems from the timing of irrigation and its influence on land-atmosphere coupling strength. Together these effects result in asymmetric temperature responses, with a more pronounced cooling during hot and/or dry periods. The influence of irrigation is even more pronounced when considering subgrid-scale model output, suggesting that local effects of land management are far more important than previously thought. Our results underline that irrigation has substantially reduced our exposure to hot temperature extremes in the past and highlight the need to account for irrigation in future climate projections.

  4. VALUE CHAIN ANALYSIS FOR LIVESTOCK FEED PRODUCTION USING SALINE IRRIGATION DRAINAGE WATER IN TURKMENISTAN

    Directory of Open Access Journals (Sweden)

    Stanley JOHNSON

    2013-01-01

    Full Text Available Irrigation return flows increase the salt concentrations of receiving water bodies and cause water logging which affect agricultural productivity in Turkmenistan. Flooding irrigation drainage water using on natural pastures has also had adverse effects on the long-term productivity of desert ranges. This study examines the economics of halophytes as feed for sheep using saline irrigation water from drainage collector systems on a representative farm. Cost-benefit and rate of return analyses show that the project is economically feasible for reused water with 1400 mg/l mineralization levels or less. At higher mineral concentrations in water, or in more saline soils, bioremediation through halophyte fodder production can be profitably implemented if new market incentives exist. Value chain analysis is applied to evaluate alternative incentive systems for sheep operations based on saline water irrigated halophyte fodder production.

  5. Effects of irrigation water supply variations on limited resource farming in Conejos County, Colorado

    Science.gov (United States)

    Eckert, Jerry B.; Wang, Erda

    1993-02-01

    Farms in NE Conejos County, Colorado, are characterized by limited resources, uncertain surface flow irrigation systems, and mixed crop-livestock enterprise combinations which are dependent on public grazing resources. To model decision making on these farms, a linear program is developed stressing enterprise choices under conditions of multiple resource constraints. Differential access to grazing resources and irrigation water is emphasized in this research. Regarding the water resource, the model reflects farms situated alternatively on high-, medium-, and low-priority irrigation ditches within the Alamosa-La Jara river system, each with and without supplemental pumping. Differences are found in optimum enterprise mixes, net returns, choice of cropping technology, level of marketings, and other characteristics in response to variations in the availability of irrigation water. Implications are presented for alternative improvement strategies.

  6. IRRIGATION OF ORNAMENTAL PLANT NURSERY

    Directory of Open Access Journals (Sweden)

    Eduardo de Aguiar do Couto

    2013-01-01

    Full Text Available Airports consume significant amounts of water which can be compared to the volume consumed by mid-size cities, thus practices aimed at reducing water consumption are important and necessar y. The objective of this study was to assess the reuse potential of sewage effluent produced at a mid-size international airport for nursery irri gation. The sewage treatment system consisted of a facultative pond followed by a constructed wetland, which were monitored during one hydrological year a nd the parameters COD, pH, solids, nitrogen, phosphorus and Escherichia coli we re analyzed. Removal efficiencies of 85% and 91% were achieved for C OD and solids, respectively. Removal efficiencies for ammonia nitrogen a nd total phosphorus were 77% and 59%, respectively. In terms of E. coli concen tration, the treated effluent met the recommendations by the World Health Organization for reuse in irrigation with the advantage of providing high levels of residual nutrient. The ornamental species Impatiens walleriana was irrigated with treated sewage effluent and plant growth characteristics were evalua ted. The experiment showed that reuse can enhance plant growth without signi ficantly affecting leaf tissue and soil characteristics. This study highlighted th e importance of simple technologies for sewage treatment especially in count ries which still do not present great investment in sanitation and proved that effluent reuse for landscape irrigation can provide great savings of water and financial resources for airport environments.

  7. On the physical mechanisms governing self-excited pressure surge in Francis turbines

    Science.gov (United States)

    Müller, A.; Favrel, A.; Landry, C.; Yamamoto, K.; Avellan, F.

    2014-03-01

    The required operating range for hydraulic machines is continually extended in an effort to integrate renewable energy sources with unsteady power outputs into the existing electrical grid. The off-design operation however brings forth unfavorable flow patterns in the machine, causing dynamic problems involving cavitation, which may represent a limiting factor to the energy production. In Francis turbines it is observed that the self-excited oscillation of a vortex rope in the draft tube cone prevents the delivery of maximum power when required. This phenomenon is referred to as full load pressure surge and has been the object of extensive research during the past decades. Several contributions deepened its understanding through measurement and simulation of the local flow properties and the global stability parameters. The draft tube pressure level and the runner outlet swirl are identified as key variables in the modelling of the vortex rope dynamics. Recently, a cyclic appearance of blade cavitation has been observed at overload conditions in a multiphase numerical simulation coupling the runner and the draft tube. From the analysis of the simulation it becomes obvious that the cyclic appearance of blade cavitation has a direct effect on the runner outlet swirl, thus introducing an additional interaction mechanism that is not accounted for in formerly published models. For the presented work, the results of this numerical study are confirmed experimentally on a reduced scale model of a Francis turbine. Several wall pressure measurements in the draft tube cone are performed, together with high speed visualizations of the vortex rope and the blade cavitation. The flow swirl is calculated based on Laser Doppler Velocimetry measurements. A possible mechanism explaining the coupling between the self-excited pressure and vortex rope oscillation and the cyclic appearance of the blade cavitation is proposed. Furthermore, the streamwise propagation speed of the flow

  8. Small-Incision Laparoscopy-Assisted Surgery Under Abdominal Cavity Irrigation in a Porcine Model

    Science.gov (United States)

    Ishii, Takuro; Aoe, Tomohiko; Yu, Wen-Wei; Ebihara, Yuma; Kawahira, Hiroshi; Isono, Shiro; Naya, Yukio

    2016-01-01

    Abstract Background: Laparoscopic and robot-assisted surgeries are performed under carbon dioxide insufflation. Switching from gas to an isotonic irrigant introduces several benefits and avoids some adverse effects of gas insufflation. We developed an irrigating device and apparatus designed for single-incision laparoscopic surgery and tested its advantages and drawbacks during surgery in a porcine model. Materials and Methods: Six pigs underwent surgical procedures under general anesthesia. A 30-cm extracorporeal cistern was placed over a 5–6-cm abdominal incision. The abdomen was irrigated with warm saline that was drained via a suction tube placed near the surgical field and continuously recirculated through a closed circuit equipped with a hemodialyzer as a filter. Irrigant samples from two pigs were cultured to check for bacterial and fungal contamination. Body weight was measured before and after surgery in four pigs that had not received treatments affecting hemodynamics or causing diuresis. Results: One-way flow of irrigant ensured laparoscopic vision by rinsing blood from the surgical field. Through a retroperitoneal approach, cystoprostatectomy was successfully performed in three pigs, nephrectomy in two, renal excision in two, and partial nephrectomy in one, under simultaneous ultrasonographic monitoring. Through a transperitoneal approach, liver excision and hemostasis with a bipolar sealing device were performed in three pigs, and bladder pedicle excision was performed in one pig. Bacterial and fungal contamination of the irrigant was observed on the draining side of the circuit, but the filter captured the contaminants. Body weight increased by a median of 2.1% (range, 1.2–4.4%) of initial weight after 3–5 hours of irrigation. Conclusions: Surgery under irrigation is feasible and practical when performed via a cistern through a small abdominal incision. This method is advantageous, especially in the enabling of continuous and free

  9. Feasibility of Natore Rubber Dam on Mahanonda River in Bangladesh and its Performance on Irrigation

    Directory of Open Access Journals (Sweden)

    Md. Sazadul Hasan

    2016-07-01

    Full Text Available Low rainfall in winter causes a great problem on irrigation. Bangladesh Agricultural Research Council (BARC started research on this problem from 1974. In 1994-95, Rubber Dam projects have been taken by BIC (Beijing IWHR Corporation in Bangladesh as it is very convenience and effective in both irrigation and cultivation of crops in winter. After installing, it is very important and challenging task to study the suitability and effect of Rubber Dam on agriculture. In this research work, the analysis of Rubber Dam in Natore, Bangladesh and its suitability on Mahanonda River has been analyzed and also studied its performance on irrigation. Also Bakkhali and Idgaon Rubber Dam were analyzed for the performance evaluation of Rubber Dam projects in Bangladesh for irrigation development. Then, feasibility of Natore Rubber Dam was studied and briefly discussed about its probable effect and benefit on agriculture. Reservoir capacity was also determined on the basis of a theoretical concept known as flow mass curve. Results of performance evaluation in irrigation were expressed in three groups: hydraulic, agricultural and socio-economic. Results of the analyses of hydraulic indicators showed that water supply is available. Agricultural performance, evaluated in terms of irrigated area was satisfactory. Analyses of socio-economic indicators showed that the Rubber Dam projects were financially viable in terms of profitability of farmers. Finally results were found that, it has a great probable effect on national economic and thus an alteration method of irrigation instead of uses of ground water. Thus, a comparative capital and operation and management cost analyses of different irrigation technologies has been carried out to ascertain the viability of Rubber Dam technology in irrigation development.

  10. THEORETICAL,NUMERICAL AND EXPERIMENTAL STUDY OF WATER HAMMER IN PIPE SYSTEM WITH COLUMN SURGE CHAMBER

    Institute of Scientific and Technical Information of China (English)

    Zhou Ze-xuan; Tan Soon Keat

    2003-01-01

    A new kind of governing equations for water hammer based on the elastic column theory was proposed and adopted to analyse water hammer phenomenon in the pipe system with a vertical column surge chamber and water level fluctuation in the surge chamber during pressure transient. The wrongness existing in the classical governing equations for water hammer was analysed. A typical reservoir-valve pipe system was chosen as an example to verify the new governing equations numerically and experimentally. The finite difference method based on the method of characteristics was used to solve numerically the nonlinear characteristic equations. The temporal evolutions of transient volume flux and head and of water level fluctuation for various surge chamber configurations were worked out, assuming that the air in the surge chamber are compressible. The relevant experiment was conducted to verify the new governing equations and numerical method. The numerical and experimental results show that the new governing equations are valid and the conventional assumption that the pressure head at the base of a surge chamber equals that of the static head above it during pressure transient is not always valid. The surge chamber generally reises the period of transient pressure wave in pipe system, reduces the maximum pressure envelope and lifts the minimum envelope substantially. The water level fluctuation in the surge chamber was numerically and experimentally observed. Increasing the size of the surge chamber and/or decreasing the initial air pressure in the surge chamber enhance the effectiveness of the surge chamber in suppressing pressure wave.

  11. Effect of hurricane paths on storm surge response at Tianjin, China

    Science.gov (United States)

    Feng, Xingru; Yin, Baoshu; Yang, Dezhou

    2012-06-01

    A hurricane induced storm surge simulation system was developed for Tianjin coast, which consists of a hurricane model and a storm surge model. The peak storm surge result of the simulation agreed well with that of the observation. Three observed paths (Rita, Mimie and WINNIE) and a hypothetical path (Rita2) were chosen as the selective hurricane paths according to their positions relative to Tianjin. The sensitivity of Tianjin storm surge to the four paths was investigated using the validated storm surge simulation system. Three groups of experiments were done. In group one, the models were forced by the wind field and air pressure; in group two and three the models were forced by the wind only and the air pressure only respectively. In the experiments, the hurricane moved with a fixed speed and an intensity of 50 year return period. The simulation results show that path of the type Rita2 is the easiest to cause storm surge disaster in Tianjin, and the effect of air pressure forcing is most evident for path of the type Rita in Tianjin storm surge process. The above conclusions were analyzed through the evolution of the wind fields and the air pressure distributions. Comparing the experiment results of Group one, two and three, it can be seen that the storm surge is mainly induced by the wind forcing and the nonlinear interaction between the effect of wind forcing and air pressure forcing on the storm surge tends to weaken the storm surge.

  12. Direct Surge Margin Control for Aeroengines Based on Improved SVR Machine and LQR Method

    Directory of Open Access Journals (Sweden)

    Haibo Zhang

    2013-01-01

    Full Text Available A novel scheme of high stability engine control (HISTEC on the basis of an improved linear quadratic regulator (ILQR, called direct surge margin control, is derived for super-maneuver flights. Direct surge margin control, which is different from conventional control scheme, puts surge margin into the engine closed-loop system and takes surge margin as controlled variable directly. In this way, direct surge margin control can exploit potential performance of engine more effectively with a decrease of engine stability margin which usually happened in super-maneuver flights. For conquering the difficulty that aeroengine surge margin is undetectable, an approach based on improved support vector regression (SVR machine is proposed to construct a surge margin prediction model. The surge margin modeling contains two parts: a baseline model under no inlet distortion states and the calculation for surge margin loss under supermaneuvering flight conditions. The previous one is developed using neural network method, the inputs of which are selected by a weighted feature selection algorithm. Considering the hysteresis between pilot input and angle of attack output, an online scrolling window least square support vector regression (LSSVR method is employed to firstly estimate inlet distortion index and further compute surge margin loss via some empirical look-up tables.

  13. Assessment of Spatial Distribution and Submerged Scope for Storm Surge in the Pearl River Delta Region

    Institute of Scientific and Technical Information of China (English)

    LI Kuo; LI Guo-sheng

    2011-01-01

    The aim of this study was to explore the spatial distribution and submerged scope for storm surge in the Pearl River Delta (PRD) region.Based on the data of storm surges in the PRD region in the past 30 years, the return periods of 12 tide-gauge stations for storm surges were calculated separately with the methods of Gumbel and Pearson-iii.The data of another six tide-gauge stations in Guangdong Coast was quoted to depict the overall features of storm surges in Guangdong.Using least-square method, the spatial distribution models of storm surges in different retum periods were established to reveal the distribution rule of the set-up values of storm surges.The spatial distribution curves of storm surges in different retum periods in the PRD Region were drawn up based on the models and the terrain of Guangdong Coast.According to the curves, the extreme set-up values of storm surges in 1 000,100, 10 a return periods were determined on each spot of Guangdong Coast.Applying the spatial analysis technology of ArcGIS, with the topography data of the PRD Region, the submerged scopes of flood caused by storm surge in 1 000, 100, 10 a return periods were drawn up.The loss caused by storm surges was estimated.Results showed that the storm surges and the topography of PRD region jointly led to the serious flood in the PRD region.This assessment would be useful for the planning and design department to make decision and provide government scientific basis for storm surge prediction, coastal engineering designing and the prevention of storm surge disaster.

  14. Surges of outlet glaciers from the Drangajökull ice cap, northwest Iceland

    Science.gov (United States)

    Brynjólfsson, Skafti; Schomacker, Anders; Korsgaard, Niels J.; Ingólfsson, Ólafur

    2016-09-01

    Surface elevation and volume changes of the Drangajökull surge-type glaciers, Reykjarfjarðarjökull and Leirufjarðarjökull, were studied by comparing digital elevation models that pre-date and post-date their most recent surges. Annual glacier-frontal measurements were used to estimate average ice velocities during the last surge of the glaciers. The observations show a distinct ice discharge, most of which was from the upper reservoir areas, down to the receiving areas during the surges. The surface draw-down in the reservoir areas was usually 10-30 m during the surges, while the thickening of the receiving areas was significantly more variable, on the order of 10-120 m. Despite a negative geodetic net mass balance derived from the digital elevation models, the reservoir areas have been gaining mass since the surge terminations. This surface thickening along with considerable ablation of the receiving areas will most likely return the glacier surface profiles to the pre-surge stage. Our results indicate that (a) greatest surface thinning in the upper reservoir areas of Drangajökull rather than proximal to the equilibrium line during Vatnajökull surges and (b) development of Drangajökull surges that resembles Svalbard surge-type glaciers rather than Vatnajökull surge-type glaciers. The contrasting surge characteristics could be explained by differences in glacier geometry, topography and substratum of the Drangajökull and Vatnajökull surge-type glaciers.

  15. Confined vortices in flow machinery

    Science.gov (United States)

    Escudier, Marcel

    After noting such basic aspects of vortex flows as the concepts of supercritical and subcritical flow and vortex breakdown, swirling flow behavior in various practical devices is discussed. The devices in question encompass swirl-stabilized combustion in industrial combustion chambers, fluidic vortex amplifiers that may be used as large scale valves, turbomachine outlets that can efficiently divert axial throughflow in a tangential direction, 'cyclone' separators, turbine draft tube surge phenomena, and the Ranque-Hilsch refrigeration tube.

  16. Surge currents and voltages at the low voltage power mains during lightning strike to a GSM tower

    Energy Technology Data Exchange (ETDEWEB)

    Markowska, Renata [Bialystok Technical University (Poland)], E-mail: remark@pb.edu.pl

    2007-07-01

    The paper presents the results of numerical calculations of lightning surge currents and voltages in the low voltage power mains system connected to a free standing GSM base station. Direct lightning strike to GSM tower was studied. The analysis concerned the current that flows to the transformer station through AC power mains, the potential difference between the grounding systems of the GSM and the transformer stations and the voltage differences between phase and PE conductors of the power mains underground cable at both the GSM and the transformer sides. The calculations were performed using a numerical program based on the electromagnetic field theory and the method of moments. (author)

  17. Effects of Irrigation in India on the Atmospheric Water Budget

    NARCIS (Netherlands)

    Tuinenburg, O.A.; Hutjes, R.W.A.; Stacke, T.; Wiltshire, A.; Lucas-Picher, P.

    2014-01-01

    The effect of large-scale irrigation in India on the moisture budget of the atmosphere was investigated using three regional climate models and one global climate model, all of which performed an irrigated run and a natural run without irrigation. Using a common irrigation map, year-round irrigation

  18. Impact of climate change on irrigation requirements in terms of groundwater resources

    OpenAIRE

    Zhou, Yu; Zwahlen, François; Wang, Yanxin; Li, Yilian

    2013-01-01

    Climate change affects not only water resources but also water demand for irrigation. A large proportion of the world’s agriculture depends on groundwater, especially in arid and semi-arid regions. In several regions, aquifer resources face depletion. Groundwater recharge has been viewed as a by-product of irrigation return flow, and with climate change, aquifer storage of such flow will be vital. A general review, for a broad-based audience, is given of work on global warming and groundwater...

  19. Effect of irrigation modernization on water and nitrogen use efficiency

    Science.gov (United States)

    Jimenez Aguirre, Ma Teresa; Isidoro Ramirez, Daniel; Barros García, Rocío

    2014-05-01

    also to increases in fertilizer price. Crop N uptake relative to NF (NUEu=NU/NF) significantly increased after modernization in corn (38% in T-Irr and 66% in S-Irr) and alfalfa (732% to 938%), but remained fairly constant in cereals (72% to 77%). Overall, modernization reduced the water diverted for irrigation by 9.5 Mm3/yr, while the foreseeable increases in ETa were not presently observed, and increased water and nitrogen use efficiency, particularly in corn. The lower I and higher WUE should increase N concentrations in drainage waters. In contrast, the lower NF and higher NUEu should decrease N losses in drainage waters, counteracting the previous effect. Therefore N concentrations and loads in irrigation return flows and the concomitant N concentrations in the receiving water bodies depend on the conjunctive water and N management and should be assessed on a case by case basis.

  20. Experimental Hydro-Mechanical Characterization of Full Load Pressure Surge in Francis Turbines

    Science.gov (United States)

    Müller, A.; Favrel, A.; Landry, C.; Yamamoto, K.; Avellan, F.

    2017-04-01

    Full load pressure surge limits the operating range of hydro-electric generating units by causing significant power output swings and by compromising the safety of the plant. It appears during the off-design operation of hydraulic machines, which is increasingly required to regulate the broad integration of volatile renewable energy sources into the existing power network. The underlying causes and governing physical mechanisms of this instability were investigated in the frame of a large European research project and this paper documents the main findings from two experimental campaigns on a reduced scale model of a Francis turbine. The multi-phase flow in the draft tube is characterized by Particle Image Velocimetry, Laser Doppler Velocimetry and high-speed visualizations, along with synchronized measurements of the relevant hydro-mechanical quantities. The final result is a comprehensive overview of how the unsteady draft tube flow and the mechanical torque on the runner shaft behave during one mean period of the pressure oscillation, thus defining the unstable fluid-structure interaction responsible for the power swings. A discussion of the root cause is initiated, based on the state of the art. Finally, the latest results will enable a validation of recent RANS flow simulations used for determining the key parameters of hydro-acoustic stability models.

  1. Senegal - Irrigation and Water Resource Management

    Data.gov (United States)

    Millennium Challenge Corporation — IMPAQ: This evaluation report presents findings from the baseline data collected for the Irrigation and Water Resources Management (IWRM) project, which serves as...

  2. Vulnerability of Coastal Communities from Storm Surge and Flood Disasters.

    Science.gov (United States)

    Bathi, Jejal Reddy; Das, Himangshu S

    2016-02-19

    Disasters in the form of coastal storms and hurricanes can be very destructive. Preparing for anticipated effects of such disasters can help reduce the public health and economic burden. Identifying vulnerable population groups can help prioritize resources for the most needed communities. This paper presents a quantitative framework for vulnerability measurement that incorporates both socioeconomic and flood inundation vulnerability. The approach is demonstrated for three coastal communities in Mississippi with census tracts being the study unit. The vulnerability results are illustrated as thematic maps for easy usage by planners and emergency responders to assist in prioritizing their actions to vulnerable populations during storm surge and flood disasters.

  3. Two parametric tropical cyclone models for storm surge modeling

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-li

    2010-01-01

    In this paper,the two parametric tropical cyclone models for storm surge modeling are further developed.The analytical expressions of tangential and radial velocity distribution are derived from the governing momentum equations,based on the general symmetric pressure distribution proposed by Holland and Fujita.On the basis of the data of several tropical cyclones that occurred in East China Ocean,the shape parameter in pressure model is estimated.Finally,the Fred cyclone(typhoon 199417)is calculated,and comparisons of measured and calculated air pressures and wind speed are presented.

  4. High Resolution Hurricane Storm Surge and Inundation Modeling (Invited)

    Science.gov (United States)

    Luettich, R.; Westerink, J. J.

    2010-12-01

    Coastal counties are home to nearly 60% of the U.S. population and industry that accounts for over 16 million jobs and 10% of the U.S. annual gross domestic product. However, these areas are susceptible to some of the most destructive forces in nature, including tsunamis, floods, and severe storm-related hazards. Since 1900, tropical cyclones making landfall on the US Gulf of Mexico Coast have caused more than 9,000 deaths; nearly 2,000 deaths have occurred during the past half century. Tropical cyclone-related adjusted, annualized losses in the US have risen from 1.3 billion from 1949-1989, to 10.1 billion from 1990-1995, and $35.8 billion per year for the period 2001-2005. The risk associated with living and doing business in the coastal areas that are most susceptible to tropical cyclones is exacerbated by rising sea level and changes in the characteristics of severe storms associated with global climate change. In the five years since hurricane Katrina devastated the northern Gulf of Mexico Coast, considerable progress has been made in the development and utilization of high resolution coupled storm surge and wave models. Recent progress will be presented with the ADCIRC + SWAN storm surge and wave models. These tightly coupled models use a common unstructured grid in the horizontal that is capable of covering large areas while also providing high resolution (i.e., base resolution down to 20m plus smaller subgrid scale features such as sea walls and levees) in areas that are subject to surge and inundation. Hydrodynamic friction and overland winds are adjusted to account for local land cover. The models scale extremely well on modern high performance computers allowing rapid turnaround on large numbers of compute cores. The models have been adopted for FEMA National Flood Insurance Program studies, hurricane protection system design and risk analysis, and quasi-operational forecast systems for several regions of the country. They are also being evaluated as

  5. Coastal Flooding Hazards due to storm surges and subsidence

    DEFF Research Database (Denmark)

    Sørensen, Carlo; Knudsen, Per; Andersen, Ole B.

    Flooding hazard and risk mapping are major topics in low-lying coastal areas before even considering the adverse effects of sea level rise (SLR) due to climate change. While permanent inundation may be a prevalent issue, more often floods related to extreme events (storm surges) have the largest...... damage potential.Challenges are amplified in some areas due to subsidence from natural and/or anthropogenic causes. Subsidence of even a few mm/y may over time greatly impair the safety against flooding of coastal communities and must be accounted for in order to accomplish the economically most viable...

  6. Automation of irrigation systems to control irrigation applications and crop water use efficiency

    Science.gov (United States)

    Agricultural irrigation management to slow water withdrawals from non-replenishing quality water resources is a global endeavor and vital to sustaining irrigated agriculture and dependent rural economies. Research in site-specific irrigation management has shown that water use efficiency, and crop p...

  7. 78 FR 37538 - Idaho Irrigation District; New Sweden Irrigation District; Notice of Preliminary Permit...

    Science.gov (United States)

    2013-06-21

    ... Energy Regulatory Commission Idaho Irrigation District; New Sweden Irrigation District; Notice of... Competing Applications On April 19, 2013, the Idaho and New Sweden Irrigation Districts, filed a joint... Street, Idaho Falls, Idaho 83404; phone: (208) 522-2356. Mr. Louis Thiel, Chairman, New Sweden...

  8. Role of sediment in the design and management of irrigation canals : Sunsari Morang Irrigation Scheme, Nepal

    NARCIS (Netherlands)

    Paudel, K.

    2010-01-01

    Sediment transport in irrigation canals The sediment transport aspect is a major factor in irrigation development as it determines to a large extent the sustainability of an irrigation scheme, particularly in case of unlined canals in alluvial soils. Investigations in this respect started since Ken

  9. Factors affecting irrigant extrusion during root canal irrigation: a systematic review

    NARCIS (Netherlands)

    Boutsioukis, C.; Psimma, Z.; Sluis, van der L.W.M.

    2013-01-01

    The aim of the present study was to conduct a systematic review and critical analysis of published data on irrigant extrusion to identify factors causing, affecting or predisposing to irrigant extrusion during root canal irrigation of human mature permanent teeth. An electronic search was conducted

  10. The simulation of cropping pattern to improve the performance of irrigation network in Cau irrigation area

    Science.gov (United States)

    Wahyuningsih, Retno; Rintis Hadiani, RR; Sobriyah

    2017-01-01

    Cau irrigation area located in Madiun district, East Java Province, irrigates 1.232 Ha of land which covers Cau primary channel irrigation network, Wungu Secondary channel irrigation network, and Grape secondary channel irrigation network. The problems in Cau irrigation area are limited availability of water especially during the dry season (planting season II and III) and non-compliance to cropping patterns. The evaluation of irrigation system performance of Cau irrigation area needs to be done in order to know how far the irrigation system performance is, especially based on planting productivity aspect. The improvement of irrigation network performance through cropping pattern optimization is based on the increase of water necessity fulfillment (k factor), the realization of planting area and rice productivity. The research method of irrigation system performance is by analyzing the secondary data based on the Regulation of Ministry of Public Work and State Minister for Public Housing Number: 12/PRT/M/2015. The analysis of water necessity fulfillment (k factor) uses Public Work Plan Criteria Method. The performance level of planting productivity aspect in existing condition is 87.10%, alternative 1 is 93.90% dan alternative 2 is 96.90%. It means that the performance of the irrigation network from productivity aspect increases 6.80% for alternative 1 and 9.80% for alternative 2.

  11. Factors affecting irrigant extrusion during root canal irrigation: a systematic review

    NARCIS (Netherlands)

    Boutsioukis, C.; Psimma, Z.; van der Sluis, L.W.M.

    2013-01-01

    The aim of the present study was to conduct a systematic review and critical analysis of published data on irrigant extrusion to identify factors causing, affecting or predisposing to irrigant extrusion during root canal irrigation of human mature permanent teeth. An electronic search was conducted

  12. Role of sediment in the design and management of irrigation canals : Sunsari Morang Irrigation Scheme, Nepal

    NARCIS (Netherlands)

    Paudel, K.

    2010-01-01

    Sediment transport in irrigation canals The sediment transport aspect is a major factor in irrigation development as it determines to a large extent the sustainability of an irrigation scheme, particularly in case of unlined canals in alluvial soils. Investigations in this respect started since

  13. 77 FR 16828 - Turlock Irrigation District, & Modesto Irrigation District; Notice of Dispute Resolution Process...

    Science.gov (United States)

    2012-03-22

    ... Energy Regulatory Commission Turlock Irrigation District, & Modesto Irrigation District; Notice of... and the Modesto Irrigation District (collectively, the Districts), are co-licensees for the Don Pedro... Steelhead Full Life-Cycle Population Models; and Request 9--Effects of the Project and Related Facilities on...

  14. The Early-Warning System for incoming storm surge and tide in the Republic of Mauritius

    Science.gov (United States)

    Bogaard, Tom; de Lima Rego, Joao; Vatvani, Deepak; Virasami, Renganaden; Verlaan, Martin

    2016-04-01

    The Republic of Mauritius (ROM) is a group of islands in the South West of the Indian Ocean, consisting of the main islands of Mauritius, Rodrigues and Agalega and the archipelago of Saint Brandon. The ROM is particularly vulnerable to the adverse effects of climate change, especially in the coastal zone, where a convergence of accelerating sea level rise and increasing intensity of tropical cyclones is expected to result in considerable economic loss, humanitarian stresses, and environmental degradation. Storm surges and swell waves are expected to be aggravated through sea level rise and climate change effects on weather patterns. Adaptation to increased vulnerability requires a re-evaluation of existing preparedness measures. The focus of this project is on more effective preparedness and issuing of alerts developing a fully-automated Early-Warning System for incoming storm surge and tide, together with the Mauritius Meteorological Services and the National Disaster Risk Reduction and Management Centre (NDRRMC), such that coastal communities in Mauritius, Rodrigues and Agalega Islands are able to evacuate timely and safely in case of predicted extreme water levels. The Mauritius Early-Warning System for storm surge and tide was implemented using software from Deltares' Open-Source and free software Community. A set of five depth-averaged Delft3D-FLOW hydrodynamic models are run every six-hours with a forecast horizon of three days, simulating water levels along the coast of the three main islands. Two regional models of horizontal resolution 5km force the three detailed models of 500m resolution; all models are forced at the surface by the 0.25° NOAA/GFS meteorological forecasts. In addition, our Wind-Enhancement Scheme is used to blend detailed cyclone track bulletin's info with the larger-scale Numerical Weather Predictions. Measured data is retrieved near real-time from available Automatic Weather Stations. All these workflows are managed by the operational

  15. Effects of climate change on water abstraction restrictions for irrigation during droughts - The UK case

    Science.gov (United States)

    Rey Vicario, D.; Holman, I.

    2016-12-01

    The use of water for irrigation and on-farm reservoir filling is globally important for agricultural production. In humid climates, like the UK, supplemental irrigation can be critical to buffer the effects of rainfall variability and to achieve high quality crops. Given regulatory efforts to secure sufficient environmental river flows and meet rising water demands due to population growth and climate change, increasing water scarcity is likely to compound the drought challenges faced by irrigated agriculture in this region. Currently, water abstraction from surface waters for agricultural irrigation can be restricted by the Environment Agency during droughts under Section 57 of the Water Resources Act (1991), based on abnormally low river flow levels and rainfall forecast, causing significant economic impacts on irrigated agricultural production. The aim of this study is to assess the impact that climate change may have on agricultural abstraction in the UK within the context of the abstraction restriction triggers currently in place. These triggers have been applied to the `Future Flows hydrology' database to assess the likelihood of increasing restrictions on agricultural abstraction in the future by comparing the probability of voluntary and compulsory restrictions in the baseline (1961-1990) and future period (2071-2098) for 282 catchments throughout the whole of the UK. The results of this study show a general increase in the probability of future agricultural irrigation abstraction restrictions in the UK in the summer, particularly in the South West, although there is significant variability between the 11 ensemble members. The results also indicate that UK winters are likely to become wetter in the future, although in some catchments the probability of abstraction restriction in the reservoir refilling winter months (November-February) could increase slightly. An increasing frequency of drought events due to climate change is therefore likely to lead to

  16. Simulation of Storm Surge and Wave Due to Typhoon Isewan (5915)

    Institute of Scientific and Technical Information of China (English)

    Jin-Hee YUK; Kyeong Ok KIM; Han Soo LEE; Byung Ho CHOI

    2015-01-01

    An integrally coupled wave-tide-surge model was developed and then applied to the simulation of the wave-typhoon surge for the typhoon Isewan (typhoon Vera (5915)), which is the strongest typhoon that has struck Japan and caused incalculable damage. An integrally coupled tide-surge-wave model using identical and homogeneous meshes in an unstructured grid system was used to correctly resolve the physics of wave-circulation interaction in both models. All model components were validated independently. The storm surge and wave properties such as the surge height, the significant wave height, wave period and direction were reproduced reasonably under the meteorological forcing, which was reprocessed to be close to the observations. The resulting modeling system can be used extensively for the prediction of the storm surge and waves and the usual barotropic forecast.

  17. Effectiveness of installing two pairs of distribution surge arresters in parallel

    Energy Technology Data Exchange (ETDEWEB)

    Sugimoto, Hitoshi; Asakawa, Akira; Yokoyama, Shigeru [Central Research Institute of Electric Power Industry (Japan); Nakada, Kazuo [Hokurika Electric Power Co. (Japan)

    1999-07-01

    Lightning strokes with a large amount of energy sometimes occur on the Sea of Japan coast in winter. Winter lightning often damages overhead power distribution lines, in particular, those supplying power to high structures located in mountainous areas. We have investigated that the ratio of surge arrester outages with respect to all damaged installations on such power distribution lines is largest at approximately 50%. We have examined the effectiveness of installing two pairs of surge arresters in parallel on a single pole as a method for preventing distribution surge arrester outages experimentally. We have clarified that to install surge arresters in parallel is effective in reducing the energy absorbed by surge arresters if these surge arresters have almost the same discharge voltage and voltage-current characteristics. (author)

  18. Surface Water and Groundwater Interactions in Traditionally Irrigated Fields in Northern New Mexico, U.S.A.

    Directory of Open Access Journals (Sweden)

    Karina Y. Gutiérrez-Jurado

    2017-02-01

    Full Text Available Better understanding of surface water (SW and groundwater (GW interactions and water balances has become indispensable for water management decisions. This study sought to characterize SW-GW interactions in three crop fields located in three different irrigated valleys in northern New Mexico by (1 estimating deep percolation (DP below the root zone in flood-irrigated crop fields; and (2 characterizing shallow aquifer response to inputs from DP associated with irrigation. Detailed measurements of irrigation water application, soil water content fluctuations, crop field runoff, and weather data were used in the water budget calculations for each field. Shallow wells were used to monitor groundwater level response to DP inputs. The amount of DP was positively and significantly related to the total amount of irrigation water applied for the Rio Hondo and Alcalde sites, but not for the El Rito site. The average irrigation event DP using data for the complete irrigation season at each of the three sites was 77.0 mm at El Rito, 54.5 mm at Alcalde and 53.1 mm at Rio Hondo. Groundwater level rise compared to pre-irrigation event water levels ranged from 3 to 1870 mm, and was influenced by differences in irrigation practices between sites. Crop evapotranspiration estimates averaged across irrigation events were highest in Rio Hondo (22.9 mm, followed by El Rito (14.4 mm and Alcalde (10.4 mm. Results from this study indicate there are strong surface water-groundwater connections in traditionally irrigated systems of northern New Mexico, connections that may be employed to better manage groundwater recharge and river flow.

  19. Irrigation-based livelihood trends in river basins: theory and policy implications for irrigation development

    Science.gov (United States)

    Lankford, Bruce

    This paper examines irrigation development and policy in Tanzania utilising a livelihoods and river basin perspective. On the basis of observations, the author argues that river basins theoretically exhibit a sigmoid curve of irrigation development in three stages; proto-irrigation, irrigation-momentum and river basin management. This model arises from two governing factors. Firstly, irrigation is a complex livelihood activity that, although has benefits, also has costs, risks and alternatives that integrate across many systems; farmers implicitly understand this and enter into or keep out of irrigation accordingly. In the proto-irrigation stage, irrigators are less common, and irrigation is felt to be a relatively unattractive livelihood. In the irrigation-momentum stage, irrigators are drawn very much to irrigation in providing livelihood needs. Hence, given both of these circumstances, governments should be cautious about policies that call for the need to ‘provide irrigation’ (when farmers may not wish to irrigate) or to further increase it (when farmers already have the means and will to do so). Second, irrigation consumes water, generating externalities. Thus if irrigation momentum proceeds to the point when water consumption directly impacts on other sectors and livelihoods, (e.g. pastoralists, downstream irrigation, the environment) decision-makers should focus not necessarily on irrigation expansion, but on water management, allocation and conflict mediation. This three-stage theoretical model reminds us to take a balanced ‘livelihoods river-basin’ approach that addresses real problems in each given stage of river basin development and to develop policy accordingly. The paper contains a discussion on livelihood factors that affect entry into irrigation. It ends with a series of recommendations on policy; covering for example new large-scale systems; problems solving; and the use of an irrigation-river basin livelihoods approach. The recommendations

  20. Oxidative stress by peripheral blood mononuclear cells is increased in hypertensives with an extreme-dipper pattern and/or morning surge in blood pressure.

    Science.gov (United States)

    Maeda, Kensaku; Yasunari, Kenichi; Watanabe, Takanori; Nakamura, Munehiro

    2005-09-01

    Because oxidative stress and inflammation are known to play important roles in the pathogenesis of cardiovascular events that occur most frequently in the morning, we studied the association between reactive oxygen species (ROS) formation by polymorphonuclear leukocytes (PMNs) or mononuclear cells (MNCs) and morning blood pressure (BP) rhythm. A total of 31 hypertensives in whom ambulatory BP monitoring was performed participated in this study. They were first divided into three groups according to their nocturnal BP rhythm (non-dippers, dippers and extreme dippers), and then into two groups according to their morning BP change (surge-type and sustained-type). ROS formation by PMNs and MNCs was measured by gated flow cytometry. C-reactive protein and traditional risk factors such as age, gender, body mass index, hemoglobin A1c, and total cholesterol were also measured. ROS formation by MNCs was significantly increased in extreme dippers (vs. dippers, p<0.05, n=11) and in morning BP surge-type hypertensives (vs. sustained-type, p<0.05, n=13). In patients who were both extreme dippers and morning BP surge-types, ROS formation by MNCs was significantly higher than that in other groups. These results suggest that both extreme dippers and morning BP surge-type hypertensives may suffer increased ROS formation by MNCs, and that increased ROS formation by MNCs may underlie morning strokes.