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This article presents the investigation, analysis, and results of the intake gate closure of two vertical fixed-wheel gates at the hydroelectric project Ituango in Colombia (2400 MW) under free-flow conditions. This atypical operation was considered successful notwithstanding adverse conditions, and therefore, it can be classified as a unique operation in the field of hydraulic gates. In this article, some relevant parameters, such as the hydraulic force of the servomotor during the operation of the gate, were measured before and after the operation and analyzed, and the results were presented. A new chart is proposed for the downpull coefficient based on the collected data, which could be implemented in the closure of gates against the free flow. Considering the abovementioned factors, the authors propose some recommendations and present drawn conclusions contributing to state of the art on design, manufacturing, and operation of this type of hydraulic gates and structures for large and small dams under adverse and extreme conditions. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the flow pattern and discharge coefficient of sluice gate with the non-suppressed sill in experimental and numerical conditions. For this purpose, the sill of a rectangular cube in widths of 7.5, 10, 15, and 20 cm was installed under the sluice gate. Experimental results showed that placing a non-suppressed sill under the sluice gate by creating a failure in the flow lines causes a different flow pattern compared to the without sill state. Deviation of streamlines after colliding with the sill causes the formation of V-shaped currents. The discretization of equations for simulations were performed using VOF method. After selecting a cell with a size of 0.07 cm as the optimal cell, the RNG turbulence model was used. The results of the numerical simulation showed an acceptable agreement with the experimental results. Thus, the place of formation of V-shaped currents was transferred downstream of the sluice gate by increasing the width of the sill and the inflow discharge. The results of the study of the discharge coefficient showed that the placement of the sill with a width of 7.5 and 20 cm, increased the discharge coefficient by an average of 5.3% and 15.5% in the experimental model and 4.7% and 16% in the numerical simulation. This relationship is without sill state and with sill state with root mean square error of 0.967 and 0.968, respectively, estimated the discharge coefficient of the sluice gate. [ABSTRACT FROM AUTHOR]

Hydraulic gates are structures widely used to control discharge and runoff depth in irrigation channels, sewage treatment stations, dams, in the São Francisco River transposition system, among other hydraulic structures. Flaws in the mechanisms for opening the gates are recurrent in these structures. These failures in the operation of the gates combined with a critical event of maximum flood can lead to the collapse of the system. In this work, a study was carried out of a flow under a partially open hydraulic gate in a channel with the maximum amount level, using a CFD program, Ansys CFX. This software uses the Finite Volume Method for domain discretization. In order to generate the model, a mesh convergence test was carried out, the residues of the simulations in the permanent and transient states of the flow were also compared. The study identified a region of flow separation near the gate. Another point studied was the hydraulic pressure generated by the flood in the structure, with the finding of a region of elevation of the values of the stresses that coincides with the zone of separation of the flowe. [ABSTRACT FROM AUTHOR]

Regulators are commonly used to control and measure flows in streams and irrigation canals. Inadequate operation of regulator gates may lead to scour downstream, possibly leading to structural failure. An experimental work was conducted to study the effect of different regulator gate operation schemes on scour hole formation downstream under free-flow conditions. The experimental model consisted of five sluice gates, a solid apron, and a mobile bed (sand). One hundred and thirty-five different gate operation schemes were studied by changing the number of opened gates and the gate arrangement with different hydraulic conditions. The parameters considered in this study were the downstream Froude number, tail water depth, upstream water head, and the number of opened gates and their arrangements. A dimensional analysis was applied to obtain non-dimensional quantities that describe the different variables affecting scour downstream the gates. The obtained results of the experimental tests were analysed and graphically represented. It was observed that the number of opened gates and their arrangements had significant effects on the scour hole pattern under different hydraulic conditions. The most favourable operation case was with all five open gates opened, while the least favourable operation case was with only the side gate opened. [ABSTRACT FROM AUTHOR]

Abstract Fixed‐wheel gates with wheels mounted on both sides that roll on roller path plates are used in both emergency intake gates and spillway gates in hydrogenerating stations. Environmental corrosion along with high wheel loads cause differences in the profile of the roller path surface. Combined with the relatively high torsional stiffness of the gate end girders, a condition of wheel load redistribution occurs where some wheels are relieved of load while others are loaded beyond their maximum design values. Failure of one wheel could jeopardize the overall operation of the gate. Furthermore, frequent operation of these gates result in changes in the stress profile in both wheels and roller paths that, potentially, could lead to failure. Currently, design guidelines for gate wheels and roller paths do not consider the fatigue life of these elements. Research‐based evidence is provided to support changes to these guidelines.

Fixed‐wheel gates with wheels mounted on both sides that roll on roller path plates are used in both emergency intake gates and spillway gates in hydrogenerating stations. Environmental corrosion along with high wheel loads cause differences in the profile of the roller path surface. Combined with the relatively high torsional stiffness of the gate end girders, a condition of wheel load redistribution occurs where some wheels are relieved of load while others are loaded beyond their maximum design values. Failure of one wheel could jeopardize the overall operation of the gate. Furthermore, frequent operation of these gates result in changes in the stress profile in both wheels and roller paths that, potentially, could lead to failure. Currently, design guidelines for gate wheels and roller paths do not consider the fatigue life of these elements. Research‐based evidence is provided to support changes to these guidelines. [ABSTRACT FROM AUTHOR]

The present study focuses on out-of-plane and in-plane vibrations of sluice gates due to the fluid-structure interaction based on numerical modelling, using the finite-element method. Primarily, the vibration of the gate was restricted to a single direction, detaching the horizontal and vertical vibrations of the gate so as to exclude their interaction. Results indicated that, if the edge of the gate is bevelled at an angle of 45°, the lowest amplitudes of horizontal vibrations are obtained. Whereas the maximum horizontal vibrations are associated with the uppermost values of the reduced velocities, for example vr > 3·5, as well as the gate's normalised opening height δ/ d of about 0·8, the maximum vertical vibrations are attained for intermediate values of vr, at about 3, and δ/ d = 0·8. If both the horizontal and vertical vibrations are mutually considered, the two-dimensional reduced velocities vr x and vr y and the structural natural frequencies fx and fy become relatively different compared to these of single-way vibrations. Results also indicated that the amplitudes of the horizontal vibrations in the authors' previous analyses were considerably greater than those of single-way horizontal vibrations. The maximum amplitude of the horizontal vibrations was observed to be close to the out-of-plane natural frequency, when 3·5 < vr x < 7 and vr y > 10. For vibration frequencies close to the vertical natural frequency fy, however, the dominant vertical vibrations occur for 2 < vr y < 4. [ABSTRACT FROM AUTHOR]

Purpose High head gates are commonly used in hydropower plants for flow regulation and emergence closure. Hydrodynamic downpull can be a critical parameter in design of the lifting mechanism. The purpose of this paper is to show that a simplified two-dimensional (2D) computational fluid dynamics solution can be used in the prediction of the downpull force on the gate lip by comparison of computed results to experimentally measured data.Design/methodology/approach In this study, ANSYS FLUENT CFD software was used to obtain 2D numerical solution for the flow field around a generic gate model located in a power intake structure which was previously used in an experimental study. Description of the flow domain, computational grid resolution, requirements on setting appropriate boundary conditions and methodology in describing downpull coefficient are discussed. Total number of 245 simulations for variable gate lip geometry and gate openings were run. The downpull coefficient evaluated from the computed pressure field as function of gate opening and lip angle are compared with the experimental results.Findings The computed downpull coefficient agrees well with the previous experimental results, except one gate with small lip angle where a separation bubble forms along the lip, which is responsible from this deviation. It is observed that three-dimensional (3D) effects are confined to the large gate openings where downpull is minimum or even reversed.Research limitations/implications In large gate openings, three dimensionality of the flow around gate slots plays an important role and departure from 2D solutions become more pronounced. In that case, one might need to perform a 3D solution instead.Practical implications This paper presents a very fast and accurate way to predict downpull force on high head gates in the absence of experimental data.Originality/value An extensive amount of simulations are run within the scope of this study. It is shown that knowing its limitations, 2D numerical models can be used to calculate downpull for a wide range of gate openings without the need of expensive experimental models. [ABSTRACT FROM AUTHOR]

With the increase in water retention needs and planned river regulation, it might be important to investigate the dynamic resistance of vulnerable elements of hydroelectric power plants, including steelwater locks. The most frequent dynamic loads affecting hydroengineering structures in Poland include vibrations caused by heavy road and railway traffic, piling works and mining tremors. More destructive dynamic loads, including earthquakes, may also occur in our country, although their incidence is relatively low. However, given the unpredictable nature of such events, as well as serious consequences they might cause, the study of the seismic resistance of the steel water gate, as one of the most vulnerable elements of a hydroelectric power plant, seems to be important. In this study, a steel radial gate has been analyzed. As far as water gates are concerned, it is among the most popular solutions because of its relatively small weight, compared to plain gates. A modal analysis of the steel radial gate was conducted with the use of the FEM in the ABAQUS software. All structural members were modelled using shell elements with detailed geometry representing a real structure. Water was modelled as an added mass affecting the structure. Different water levels were used to determine the most vulnerable state of the working steel water gate. The results of the modal analysis allowed us to compare the frequencies and their eigenmodes in response to different loads, which is one of the first steps in researching the dynamic properties of steel water gates and their behaviour during extreme dynamic loads, including earthquakes. [ABSTRACT FROM AUTHOR]

The effects of a moving gate on dam break flow experiments are numerically considered in this paper. The dam break flow process is modelled by a sudden gate release. A Constrained Interpolation Profile (CIP)-based model is employed to solve the Navier-Stokes equations with the free surface boundary condition to deal with the water-air-gate interactions. In addition, the VOF-type THINC/SW method is used to capture the free surface. The movable gate is simulated by an immersed boundary, and a gate motion formula is proposed from existing experimental data and applied in the dam break flow computations. The difference between the water profile and pressure domain with/without gate motion is examined. The dam breaks with different gate motions are discussed as well. The numerical results show that the proposed gate motion formula correlates well with the numerical modelling, and the gate motion has a significant influence in the water collapse process and cannot be neglected in the study of dam break. [ABSTRACT FROM AUTHOR]

A Lopac gate is one type of upstream control structures in irrigation canals. Advantages of a Lopac gate include performing as an overflow structure, letting sediments and floating bodies pass simultaneously, as well as easy automation. The structure has recently attracted the attention of researchers for detailed investigations. One effective tool to study control structures is a mathematical model. Due to the unsteady nature of flow in irrigation canals, incorporation of the mathematical model of control structures with hydrodynamic models is necessary. In this research, a mathematical model of Lopac gates is developed and linked with the ICSS (irrigation conveyance system simulation) hydrodynamic model. The Lopac gate model was developed as a boundary condition in four subroutines, including steady flow conditions, operation, unsteady flow conditions, and updating information. The developed model is validated using physical model data. The maximum error obtained was 6%, which is acceptable for practical purposes. The model was tested on a canal of DEZ irrigation network in Iran under many different conditions. The results showed that the model is performing well for tested applications and could be used in various studies of irrigation canals equipped with this structure. [ABSTRACT FROM AUTHOR]

Metal gates of hydraulic structures are supplied with load bearing girders. Girders, crossbeams and gates require much steel when being manufactured. Girders of hydraulic gates rational design leads to considerable cost savings. The paper describes steel hydraulic girders optimal design. Steel hydraulic girders optimal design is based on the strength theory introduced by M. Huber, R. Mises, H. Hencky and on the theory of mirror functions. With the help of out-form volume we can either calculate the optimal form for a girder with variable cross-section or the optimal height for a girder of uniform cross-section. The paper introduces hydraulic girders calculations according to the authors’ methodology. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to study the dynamic performance of seals and the fatigue failure probability updating of a hydraulic steel sluice gate by experiments. First, water seal modifications involving of top, side, and bottom water seals and the rotation hinge water seal were performed in order to identify and test for the desired shape and functionality. Water sealing experiments under a variety of conditions were performed. It is indicated that the preset compressive deformation of various water seals changed at varying water head conditions. Moreover, the transformation law of the preset compressive deformation of different sealing parts under the reservoir water head was discovered. Second, a hydraulic steel gate's fatigue reliability was evaluated based on Bayes' theorem. The findings indicate that fatigue cracks can be detected for existing structures while the fatigue reliability assessment can be updated by nondestructive testing (NDT). Based on the probabilistic characteristics for NDT techniques and Bayes' theorem, a fatigue reliability updating assessment model for existing steel gate components is proposed. The results showed that fatigue reliability will increasewith no cracks detected, decrease with unknown cracks detected, and change remarkably with cracks detected. [ABSTRACT FROM AUTHOR]

Gates are useful structures that are widely used in open channels for controlling discharge and water level. In this article, to study the flow passing under a gate, five gates with different-shaped edges are numerically simulated. The contraction coefficient, discharge coefficient, pressure distribution behind the gate, and the pressure distribution on the channel bottom near the gate were investigated with models in free flow conditions. The analyses were performed for six water depths. The results show that the contraction coefficients for standard and jagged-edged shapes increase with an increase in the a/E1 ratio (where a is the gate opening and E is the energy level), which matches the experimental results. For upward- and downward-facing sharp edges and for rounded-edged gates, the contraction coefficient decreases until a/E1 < 0.4 and increases for a/E1 > 0.4. Investigation of pressure distribution behind the gate and on the bottom of the channel under the gate shows that the position of maximum pressure is the same for all models, but its magnitude varies among different models. Comparison of numerical analysis results with experimental and theoretical data showed good agreement. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hydraulic gates need to be light-weight, corrosion-resistant, maintenance-free, and durable with high endurance under fatigue loads. All of these requirements could be challenges to be met using conventional materials like steel and concrete. However, with the emergence of advanced Fiber Reinforced Polymer (FRP) composites for waterway structures, it has now been possible to achieve all of these physical and performance requirements in a cost-effective manner. Due to their lightness, excellent corrosion and wear resistance along with superior thermo-mechanical properties, FRPs have emerged as one of the best alternatives in the field of civil infrastructure. This paper covers several aspects of the design, manufacturing, testing, analysis, and field implementation of a novel integrated FRP wicket gate in Mississippi River lock and dam. The cellular FRP panel with foam core and integrated stiffening and fastening components has been analyzed to compute the bending stiffness both theoretically and experimentally and a good correlation has been obtained. [ABSTRACT FROM AUTHOR]

Tide gates, used to regulate tidal flow as part of land reclamation programmes, temporally block fish movement by closing during the flood tide. Their impact on the upstream movement of brown trout, Salmo trutta , and other fish species has received little consideration. The River Stiffkey, UK, discharges into the North Sea via three top-hung tide gates, one counterbalanced (Gate 1), and two not (collectively referred to as Gate 2). Three-hundred adult trout were caught between 0.5 and 6.0 km upstream from the gates on 20 separate days between July and December 2011 ( n = 15 per day) and implanted with 23 mm half-duplex Passive Integrated Transponder (PIT) tags before being released 15 m downstream from Gate 1 where PIT antennas were located on either side. Overall, gate attraction (percentage of fish released that were detected by at least one antenna) and passage efficiencies (number of fish that passed Gate 1 reported as a proportion of those that approached) were 96.7% and 92.4%, respectively. The operation of an orifice, installed to improve connectivity for adult trout and juvenile eels, did not influence passage efficiency or delay. Of the fish that passed Gate 1 when the orifice was operational, 42.6–55.7% approached the orifice entrance and 70.6–92.3% of these passed through. Individuals that passed through the orifice were larger than those that did not. Movement past the tide gates (median duration = 6.04 h) took 6 times longer than passage through two unimpeded reaches upstream. Duration of passage through the gates was predominately related to the mean angle of gate opening during the time prior to passage, followed by water temperature. Overall, a counterbalanced top-hung tide gate delayed the upstream movement of brown trout, highlighting a need to assess and potentially mitigate the impact of gates with more restrictive opening apertures and durations. [ABSTRACT FROM AUTHOR]

The use of aqueous solutions as the gate medium is an attractive strategy to obtain high charge carrier density (10 12 cm −2 ) and low operational voltages (<1 V) in organic transistors. Additionally, it provides a simple and favorable architecture to couple both ionic and electronic domains in a single device, which is crucial for the development of novel technologies in bioelectronics. Here, we demonstrate the operation of transistors containing copper phthalocyanine (CuPc) thin-films gated with water and discuss the charge dynamics at the CuPc/water interface. Without the need for complex multilayer patterning, or the use of surface treatments, water-gated CuPc transistors exhibited low threshold (100 ± 20 mV) and working voltages (<1 V) compared to conventional CuPc transistors, along with similar charge carrier mobilities (1.2 ± 0.2) x 10 −3 cm 2 V −1 s −1 . Several device characteristics such as moderate switching speeds and hysteresis, associated with high capacitances at low frequencies upon bias application (3.4–12 μF cm −2 ), indicate the occurrence of interfacial ion doping. Finally, water-gated CuPc OTFTs were employed in the transduction of the biospecific interaction between tripeptide reduced glutathione (GSH) and glutathione S-transferase (GST) enzyme, taking advantage of the device sensitivity and multiparametricity. [ABSTRACT FROM AUTHOR]

Traditional meter gates for farm delivery flow measurement from an open channel conveyance have traditionally incorporated round canal gates (Armco type) for control. In recent years, some irrigation water agencies (i.e., irrigation districts) have replaced deteriorating round gates with lower-cost rectangular gates that cover round holes. Similar to the situation described in a companion paper, where round gates were examined, there have been no investigations into flow measurement uncertainty using the existing rating tables for these gates. In this study, two commonly used rectangular gate sizes, 0.46 m (18-in.) and 0.61 m (24-in.), were tested under scenarios of various gate openings, upstream heads, and head differences. Coefficient of discharge (Cd) values were computed based on actual gate open areas. These improved Cd values were used to generate new discharge rating tables for 0.46 m (18-in.) and 0.61 m (24-in.) rectangular meter gates. Limitations for these rectangular gates are discussed. If guidelines presented in this paper and in the companion paper are followed, the average instantaneous flow measurement uncertainty that could be expected is better than ±5%. However, uncertainty is higher (up to approximately ±9.5%) at the lower end of the recommended gate openings [0.10 m (4 in.)] for these rectangular gates. [ABSTRACT FROM AUTHOR]

Recent California legislation requires irrigation water agencies larger than 25,000 acres to measure volumetric water deliveries within specified levels of relative uncertainty. Although the meter gate is one of the most widely used flow measurement devices in California, little investigation has been conducted into the accuracy, limitations, and uncertainties of the rating tables developed over 60 years ago. A meter gate testing facility was constructed at the Cal Poly Irrigation Training and Research Center's Water Resources Facility capable of testing gates up to 0.76 m (30 in.). The facility was constructed with gates oriented perpendicular to the supply channel flow to match actual field conditions. Three commonly used gate sizes of 0.30 m (12 in.), 0.46 m (18 in.), and 0.61 m (24 in.) were examined under a variety of upstream head, head loss, and gate opening conditions. Based on the limitations, guidelines are included to assist users and lower the uncertainty of these devices. It was found that meter gates can be an accurate flow measurement device if installed and operated correctly according to guidelines provided. Limitations were found: upstream head above the top of the turnout pipe must be maintained equivalent to at least half the pipe diameter, and gate openings less than 25% open can lead to large uncertainties. Using the new rating tables for the three gates examined, the relative uncertainty is less than ±5 to ±7% at the 95% confidence level with the new rating tables, as compared with less than ±10% at a 95% confidence level using common published tables. Uncertainties are lower than the required estimated 10.7% instantaneous flow rate uncertainty that will be needed to meet current SB X7-7 requirements. [ABSTRACT FROM AUTHOR]

A water-gated field effect transistor (WG-FET) with 16-nm-thick single crystalline silicon film is realized for the first time and tested with both probe and planar gate electrode structures. Simple and cheap process steps make it suitable for low cost applications. Planar gate electrode topology simplifies the integration of transistors on the same die. Water as gate dielectric provides compatibility with fluidic devices. The transistor works below 1 V and has a threshold voltage, V th , of -0.18 V for probe gate and -0.09 V for planar gate electrode. On/off ratios for probe and planar gate structures are measured as 14000A/A and 250A/A, respectively. [ABSTRACT FROM AUTHOR]

Anions play a crucial role in locking alkali metals on the interior of metal-organic capsules that contain structural water gates. This role is further evidenced when stitching-up the capsule seam, resulting in either expulsion or trapping of cesium ions depending on the anion employed. [ABSTRACT FROM AUTHOR]

An experimental study of two model-scale lens-shaped vertical gates consisting of a truss and plate is presented. Experimental results are applied to the design of the new Nakdong River gates in Busan, South Korea, for flood and irrigation control. Experimental models are developed using finite-element (FE) analysis. A 1:31 scale model is constructed for the short gate (47.5 m wide, 8.5 m high at full scale) using acrylic, and a 1:61 scale model is constructed for the long gate (95 m wide, 8.5 m high at full scale) using an acrylic truss and acrylonitrile butadiene styrene plate. Natural frequencies of the model gates are measured and calibrated with FE predictions. Dynamic characteristics of the flow-induced vibration are compared for two gate orientations. Vibrations of the model gates in Orientation 1 (plate convex in the upstream direction) and Orientation 2 (plate convex in the downstream direction) are measured for various flow conditions. A combination of bottom opening heights and upstream and downstream water levels is tested in an experimental 1.6-m-wide channel. Hydrodynamic vibrational characteristics of the two experimental gate models are analyzed and compared as a function of upstream (river) level, downstream (sea) level, and bottom opening height. Results from the analysis are used to determine the appropriate gate orientation and incorporated into the final design of the bottom shapes of the prototype gates. The test results also provide a basic dataset for development of operations guidelines to minimize flow-induced vibrations of the gates. [ABSTRACT FROM AUTHOR]

An experimental study is combined with numerical modelling to investigate new ways to reduce cross-flow vibrations of hydraulic gates with underflow. A rectangular gate section placed in a flume was given freedom to vibrate in the vertical direction. Horizontal slots in the gate bottom enabled leakage flow through the gate to enter the area directly under the gate which is known to play a key role in most excitation mechanisms. For submerged discharge conditions with small gate openings the vertical dynamic support force was measured in the reduced velocity range 1.5< V r <10.5 for a gate with and without ventilation slots. The leakage flow significantly reduced vibrations. This attenuation was most profound in the high stiffness region at 2< V r <3.5. Two-dimensional numerical simulations were performed with the Finite Element Method to assess local velocities and pressures for both gate types. A moving mesh covering both solid and fluid domain allowed free gate movement and two-way fluid–structure interactions. Modelling assumptions and observed numerical effects are discussed and quantified. The simulated added mass in still water is shown to be close to experimental values. The spring stiffness and mass factor were varied to achieve similar response frequencies at the same dry natural frequencies as in the experiment. Although it was not possible to reproduce the vibrations dominated by impinging leading edge vortices (ILEV) at relatively low V r , the simulations at high V r showed strong vibrations with movement-induced excitation (MIE). For the latter case, the simulated response reduction of the ventilated gate agrees with the experimental results. The numerical modelling results suggest that the leakage flow diminishes pressure fluctuations close to the trailing edge associated with entrainment from the wake into the recirculation zone directly under the gate that most likely cause the growing oscillations of the ordinary rectangular gate. [ABSTRACT FROM AUTHOR]

In 2011, Japan was hit by a tsunami that was generated by the greatest earthquake in its history. The first tsunami warning was announced 3 min after the earthquake, as is normal, but failed to estimate the actual tsunami height. Most of the structural countermeasures were not designed for the huge tsunami that was generated by the magnitude M = 9.0 earthquake; as a result, many were destroyed and did not stop the tsunami. These structures included breakwaters, seawalls, water gates, and control forests. In this paper we discuss the performance of these countermeasures, and the mechanisms by which they were damaged; we also discuss damage to residential houses, commercial and public buildings, and evacuation buildings. Some topics regarding tsunami awareness and mitigation are discussed. The failures of structural defenses are a reminder that structural (hard) measures alone were not sufficient to protect people and buildings from a major disaster such as this. These defenses might be able to reduce the impact but should be designed so that they can survive even if the tsunami flows over them. Coastal residents should also understand the function and limit of the hard measures. For this purpose, non-structural (soft) measures, for example experience and awareness, are very important for promoting rapid evacuation in the event of a tsunami. An adequate communication system for tsunami warning messages and more evacuation shelters with evacuation routes in good condition might support a safe evacuation process. The combination of both hard and soft measures is very important for reducing the loss caused by a major tsunami. This tsunami has taught us that natural disasters can occur repeatedly and that their scale is sometimes larger than expected. [ABSTRACT FROM AUTHOR]

This paper presents new smooth upstream face high head gate form that heavily reduces hydrodynamic forces in conjunction to a total absence of uplift (negative downpull) forces. The research work at the Institute of Hydraulic Engineering investigated techniques to reduce the hydrodynamic load on high head gates. Task was achieved with the new smooth upstream high head leaf gate; improved safety for the hydro-machinery equipment and also for concerned parts of the whole project, while minimizing costs. [ABSTRACT FROM AUTHOR]

Abstract: The flow movement through a sluice gate is investigated for both free and submerged flow conditions. For free flow condition, the current dimensionless formula, indicated acceptable accuracy; while for submerged flow condition it was modified especially for low submerged condition. In this regard, Buckingham theorem along with the Incomplete Self-Similarity concept was employed and a new stage–discharge relationship was developed accordingly. Also, to achieve a suitable formula for submerged flow condition being accurate in low submergence, the maximum tailwater depth allowing the free flow condition and head loss factor were identified as missing parameters in the functional dimensional equation. Based on employing these parameters the function of Discharge Reduction Factor (DRF) was defined. [Copyright &y& Elsevier]

Abstract: One observed vibration mode for Tainter gate skinplates involves the bending of the skinplate about a horizontal nodal line. This vibration mode can be approximated as a streamwise rotational vibration about the horizontal nodal line. Such a streamwise rotational vibration of a Tainter gate skinplate must push away water from the portion of the skinplate rotating into the reservoir and draw water toward the gate over that portion of the skinplate receding from the reservoir. The induced pressure is termed the push-and-draw pressure. In the present paper, this push-and-draw pressure is analyzed using the potential theory developed for dissipative wave radiation problems. In the initial analysis, the usual circular-arc skinplate is replaced by a vertical, flat, rigid weir plate so that theoretical calculations can be undertaken. The theoretical push-and-draw pressure is used in the derivation of the non-dimensional equation of motion of the flow-induced rotational vibrations. Non-dimensionalization of the equation of motion permits the identification of the dimensionless equivalent added mass and the wave radiation damping coefficients. Free vibration tests of a vertical, flat, rigid weir plate model, both in air and in water, were performed to measure the equivalent added mass and the wave radiation damping coefficients. Experimental results compared favorably with the theoretical predictions, thus validating the theoretical analysis of the equivalent added mass and wave radiation damping coefficients as a prediction tool for flow-induced vibrations. Subsequently, the equation of motion of an inclined circular-arc skinplate was developed by incorporating a pressure correction coefficient, which permits empirical adaptation of the results from the hydrodynamic pressure analysis of the vertical, flat, rigid weir plate. Results from in-water free vibration tests on a 1/31-scale skinplate model of the Folsom Dam Tainter gate are used to demonstrate the utility of the equivalent added mass coefficient. [Copyright &y& Elsevier]

The gravity-driven free surface flow problems for which both the solid and free surface boundaries are highly curved are very difficult to solve. A computational scheme using a variable domain and a fixed domain natural element method (NEM) is developed in the present study for the computation of the free surface profile, velocity and pressure distributions, and the flow rate of a 2D gravity fluid flow through a conduit and under a radial gate. The problem involves two highly curved unknown free surfaces and arbitrary curved-shaped boundaries. These features make the problem more complicated than flow under a sluice gate or over a weir. The fluid is assumed to be inviscid and incompressible and the results obtained are confirmed by conducting a hydraulic model test. The results are in agreement with other flow solutions for free surface profiles and pressure distributions. [ABSTRACT FROM AUTHOR]

The flow characteristics upstream and downstream of sluice gates are studied experimentally and numerically using Reynolds averaged Navier-Stokes two-dimensional simulations with a volume of fluid method. Special attention was brought to large opening and submergence, a frequent situation in distribution canals that is little seldom addressed in the literature. Experimental results obtained by ADV measurements provide mean velocity distributions and turbulence characteristics. The flow is shown to be mostly two-dimensional. Velocity fields were simulated using renormalization group k-epsilon and Reynolds stress model turbulence models, leading to an estimation of energy and momentum correction coefficients, head loss, and bed friction. The contraction coefficient is also shown to increase with gate opening at large submergence, which is consistent with the energy-momentum balance. This result can be used to derive accurate discharge equations. [ABSTRACT FROM AUTHOR]

On March 11, 2011, at 14:46 local time, a powerful earthquake occurred off the Sanriku coast of northeastern Japan. It was immediately apparent that this was the strongest earthquake on the historical record, and the resulting series of tsunami ravaged the Tohoku region. In Iwate Prefecture, the tsunami height generally exceeded the design tsunami level for safety, which had been determined on the basis of the 1896 Meiji-Sanriku tsunami, the 1933 Showa-Sanriku tsunami, and the 1960 Chile tsunami. As of January 10, the number of dead and missing in Iwate rose to 6,035. Over 24,000 buildings had been destroyed. After the 1933 Showa-Sanriku, disaster prevention facilities were built along the coast. However, many tsunami seawalls and water gates suffered enormous damage from the impact of the 2011 Tohoku Tsunami. This paper sketches out the characteristics and scope of the damage in the coastal areas of Iwate Prefecture, with a particular focus on the northern coast of Iwate. [ABSTRACT FROM AUTHOR]

Abstract: Identifying the free or submerged flow condition and the threshold between the two regimes is vital for accurate flow measurement through a gate. In this paper, analytical findings about distinguishing condition curve of radial gates are presented. The generality of the available calibration methods of the radial gates has been analyzed. Then, based on the assumption of starting the transition zone right at the interception point of the free and submerged flow relationships, a comprehensive equation is developed to distinguish the flow condition through a radial gate. Using ample high quality available experimental data, the accuracy of the proposed distinguishing curve was verified. The results indicated that the proposed distinguishing curve accurately identified observed flow condition data. Finally, by defining a suitable sensitivity index, the effects of downstream channel width, energy loss through the gate, Reynolds number, and contraction coefficient on the distinguishing condition curve have been evaluated. Also, the results promise the application of the proposed method for situations where only one of some parallel radial gates is operating under the submerged flow condition. [Copyright &y& Elsevier]

This study was undertaken to assess the potential impacts of climate change on agriculture in the Sikasso region of southern Mali, as part of an effort by the U.S. Agency for International Development (USAID) to integrate climate change adaptation considerations into their development projects. The region is considered to be the breadbasket of Mali, providing a substantial amount of the country's food supplies as well as cotton for exchange earnings. The project had two components: modeling how climate change could affect production of cereal and cash crops in southern Mali; and conducting a stakeholder-driven vulnerability and adaptation assessment to identify potential options for addressing current and projected risks to agriculture from climate change. Projected changes in crop yields were based on a previous analysis that was extended for the purposes of this study. The projections suggested that the sensitivity of maize to changing weather conditions is relatively small (generally less than 10% change) under both dry and wet scenarios in 2030 and 2060. White (Irish) potatoes, the primary cash crop, are the most sensitive to changing weather conditions, with yields decreasing under both dry and wet conditions; yields could decrease by about 25% by 2060. Stakeholder workshops, field interviews, and an expert analysis were used to assess current and future climate-related vulnerability and to identify potential adaptation options. The main focus of the assessment was farmers in a village of about 3,000 people in the Sikasso region that practiced a rice-potato rotation system typical to the region. The farmers emphasized adaptation measures that require outside financial and technical assistance, for example installation of a water gate that would retain more water in the inland valley and increase the water table to flood rice fields during the rainy season and for furrow irrigation of potatoes during the dry season. Adaptations emphasized by both the farmers and representatives of regional technical services were crop diversification and germplasm improvement; soil and water management; access to equipment (plows, carts, oxen, and improved stoves); credit stockage villageois (CSV); and fertilizer. [ABSTRACT FROM AUTHOR]

The Coorong is an elongated coastal lagoon system in southern Australia whose major freshwater input occurs through a series of barrages separating it from an adjacent lake. The connectedness of the lagoon to the sea continuously evolves as its Mouth channel is scoured by sustained outflows associated with barrage discharges or is infilled with sand during times of zero flows. A key driver of the Coorong dynamics is oceanic water-level fluctuations propagating into the lagoon, and the representation of the continuously changing transmission properties of the Mouth channel for these fluctuations is a necessary requirement for the successful modelling of these dynamics. This paper applies a methodology for estimating the effective bed elevation and width of the Mouth channel by considering how oceanic water-level fluctuations propagate into the Coorong. The analysis applied to 22 years of measurements shows how the effective depth of the Mouth channel has been highly dynamic, varying between more than 5 m to less than 0.5 m depending on barrage flows. A simple algorithm is developed that well represents the time series of effective bed elevations as a function of Mouth channel outflow. This algorithm enables the hydrodynamic modelling of the Coorong to be undertaken to assess the impact on the lagoon of alternative barrage release strategies. [ABSTRACT FROM AUTHOR]

The critical hydraulic configuration for a set of torque-tube gates controlling the flow through the navigable portion of a spillway was experimentally identified. In this paper, an analytical model for the upstream pressure field on a typical gate within the set is constructed. The gate rotation from the maximum elevation (gate in closed position) and the hydraulic torque transmitted by the pressure field to the gate tube are formulated. Mean values of parameters of response are often sufficient for the preliminary design of a gate. The dispersions of these parameters of response, which are necessary for the final design of a gate, may be computed using the corresponding mean-square values. These were obtained empirically in a flume from experiments on a 1/15-scale physical model of a set of three prototype gates for the Montgomery Point Lock and Dam project. Theoretical predictions of parameter mean and mean-square values compare well with the average corresponding statistics obtained experimentally. [ABSTRACT FROM AUTHOR]

Based on experimental measurements and observations in a laboratory channel, the hydrodynamic behaviour of the approaching flow and the amount of sediment entering a right-angled lateral intake in a diversion dam were investigated. The velocity field, both upstream of the intake in the main channel and in front of the intake in the sluiceway, were measured under various discharge combinations of the river, intake and sluice gate. In addition, velocity profiles both upstream and downstream of the intake and the amount of sediment entering it were measured. Analysis of the velocity data showed that the discharge of the sluice gate played an important role in determining the velocity profile and also the mechanism of sediment entry. All velocity profiles where the sluice gate was closed had an inflection point, where the flow direction changed, leading to a return velocity near the bed. The elevation of this point was a function of the intake discharge and approximately equal to the height of the entrance sill. Experimental observation showed that sediment entered the intake by a tornado-like vortex. The strength and frequency of the vortices depended on the intake and sluice gate discharges. Analysis of the sedimentation data showed that the amount of sediment entering the intake increased with increasing intake discharge. In addition, an increase in the sluice gate discharge caused an increase of sediment entry to the intake under the same intake discharge. [ABSTRACT FROM AUTHOR]

Tasks and methods of solution pertaining to estimation of technical condition of unique and large-size mechanism on the basis of theoretical models of its functioning are discussed. Practical applications of such models for proving of the motion parameters, loads on elements and driving forces of the real mechanism are illustrated. [ABSTRACT FROM AUTHOR]

Adequate and reliable parameters are key to the sustainable management of vital groundwater resources. Present study focuses on the evaluation of direct methods (tidal efficiency and time lag methods) and an extended tide-aquifer interaction technique for determining the hydraulic parameter of coastal unconfined and confined aquifer systems. The hydraulic diffusivities of unconfined and confined aquifer systems were estimated using the tidal efficiency and time lag methods as well as they were optimized using the tide-aquifer interaction model and the Levenberg-Marquardt optimization technique. The hydraulic diffusivities were optimized by the Levenberg-Marquardt technique following two approaches: lumped tidal component approach and multi-tidal component approach. The effect of spring and neap tidal data on parameter estimates was also analyzed. The tide-aquifer interaction data for two unconfined sites and three confined sites were used in this study. For all the five sites under study, the aquifer hydraulic diffusivities based on the time lag method were found to be much larger (2 to 14 fold for the unconfined sites and 5 to 8 fold for the confined sites) than those based on the tidal efficiency method. The analysis of the optimization results indicated that the hydraulic diffusivities following "multi-tidal component approach" are more reliable and accurate for both unconfined and confined aquifers than those obtained following "lumped tidal component approach". Consequently, the use of "multi-tidal component approach" is strongly recommended for the determination of aquifer parameters by the tide-aquifer interaction technique. Furthermore, the tide-interaction data corresponding to spring and neap tidal events were found to significantly affect the aquifer diffusivities yielded by the tide-aquifer interaction technique. It is concluded that a judicious use of tide-aquifer interaction technique is indispensable for the reliable estimates of hydraulic parameters of coastal aquifer systems. [ABSTRACT FROM AUTHOR]

Computational results are presented for uniform approach flow past emergency gate model, placed in a 2-D channel with free water surface, for two cases: (1) fixed gate and (2) gate moving perpendicular to the water flow. The calculations were made in the dimensionless system, for the assumed Reynolds number Re = 106. The velocity field and vorticity field were determined by vortex method. On this basis the pressure distribution profile and hydrodynamic force were determined by means of boundary elements method. The vortex structures and the evolution of vortex shedding are illustrated by velocity field of vortex blobs for both cases - fixed and movable gate. We also presented the distribution of the pressure coefficient alongside the gate edge as well as the derivative lift and drag coefficients. The average force coefficients agree very well with the experimental values. The movement of downward of the gate substantially increases the calculated value of the lift coefficient. [ABSTRACT FROM AUTHOR]

This paper presents experimental and two-dimensional (2D) numerical results of four tests concerning rapidly varying flows induced by the sudden removal of a sluice gate. For the acquisition of the experimental data, an imaging technique capable of providing spatially distributed information was adopted: a coloring agent was added to the water, the opalescent bottom of the facility was backlighted, and photographs of the area of interest were taken. The gray tones of the acquired images were converted into water depths by means of transfer functions derived from a static calibration. The potential sources of error of the proposed procedure are discussed. A local comparison with an ultrasonic device showed a 20% maximum deviation in 95% of the observations. The tests were simulated through a 2D MUSCL-Hancock finite volume numerical model, based on the classical shallow water approximations, in which the intercell water depths are estimated according to the surface gradient method. A global analysis of the relative frequency distributions of the deviation between numerical and experimental results is performed. Despite some evident differences at a local scale, the adopted 2D numerical model is capable of reproducing the main features of the flow fields under investigation. [ABSTRACT FROM AUTHOR]

A vortex method for simulating a flat flow within moving complex boundaries is presented. Thanks to the use of Lagrange variables (the trajectories of vortex particles) to determine the evolution of vorticity and velocity fields the method offers the possibility of modelling high Reynolds number flows. A procedure for formulating boundary conditions for flows confined by a moving impervious boundary, consisting in the superposition of three velocity fields: the first originating from the vortex particles, the second being a potential field satisfying the no-through-flow boundary condition and the third one resulting from the fact that the vortex sheet is modelled along the impervious boundaries and satisfying the no-slip-flow condition, is described. The original derivation of a formula for vortex sheet intensity, based on the single layer potential theory and leading to the formulation a second-kind Fredholm equation for vortex sheet intensity, is presented. This paper is the first part of a work covering the theoretical foundations and general description of the vortex method algorithms and boundary conditions. An example illustrating the computation of the vorticity and velocity fields of the flow through a moving hydraulic gate will be provided in the second part of the work. [ABSTRACT FROM AUTHOR]

Two-dimensional non-linear free-surface flows in a channel bounded below by an uneven bottom with rapid changes are considered. Numerical solutions are computed by a boundary integral equation method similar to that first introduced by King & Bloor (1987, J. Fluid Mech., 182, 193–208). Free-surface flows past localized disturbances, steps and sluice gates are calculated. In addition, weakly non-linear solutions are discussed. [ABSTRACT FROM PUBLISHER]