overshot weir in stock

Waterman Tilting Weir (Overshot) Gates are an overflow-type gate used to control levels in canals, basins and other agricultural, municipal and industrial applications.

WATERMAN TILTING WEIR (OVERSHOT) GATESare an overflow-type gate used to control levels in canals, basins and other agricultural, municipal and industrial applications.

Overshot gates (also known as pivoting weir gates) are used to control upstream water levels. Versatility, efficiency, and safety are the primary reasons the Fresno Overshot Gate is the method of choice for municipal, agricultural, and industrial canal water control.

I am using a sluice gate with an ogee inline structure. I have never worked directly with an ogee weir and HEC-RAS asks for inputs like "Spillway approach height", and "Design energy head". I am not quite sure what this is in reference too. Is there a post or reference manual somewhere that explains this more in depth?

Hmm. Since I do not readily have the design specs for this dam to get the design energy head, could I just do a sensitivity analysis (low/high/mid) for the weir coefficient that those two parameters are used to calculate and go with the more conservative value?

Chris, we have a model with these sorts of overshot gates, that run the entire length of a dam. We are modeling these gates as initially closed, and as a large hydrograph comes through the gates fail and are fully open. Then during the same hydrograph we are trying to model a breach of the inline structure. However, the results of the "with breach" case match the results of the "no breach" case exactly. It"s as though RAS is treating the breach opening like it"s not there, or that water cannot flow through it. Is this true for RAS, that it does not recognize a breach that is below an overshot gate? I ask because if we take the gate out and just pretend that they were open the whole time so that there is only the inline structure, the resulting hydrograph shows the impact of the breach. Thanks Chris.

Hi, I am a relatively new user. I am confused about a simple thing. I want to model a overflow structure with around 15 gate openings. Do I need to draw a solid embankment extending from the starting to the ending of the gates using the weir/embankment option under inline structure before defining the gates? Or do I need to keep opening in the embankment?

I like to model radial gates and sluice gates with broad crested weir. Is it possible to use broad crested weir with radial gates. Even though in the selection dialogue box it is there, I doubt that, as all the explanations related with radial gates are drawn with ogee spillway.

York Civil Pty Ltd engaged AWMA to custom design vertical water control gates, fishway gates and hydraulic actuation systems for SA Water’s Pipeclay and Slaney Weirs.

Five large AWMA Fixed Base Overshot (decant) gateswere developed to simulate overshot flow patterns of the existing stoplogs, whilst Segmented Stopboards were supplied for the new environmental fishways.

The overshot gate leaves were manufactured from marine grade aluminium with grade 316 stainless steel embedded frames and stainless steel dual cylinder actuation systems.

Marine grade aluminium segmented stopboards and AWMA lifting ladders were supplied for the fishway gates. Design features include overshot flows with low velocities for safe fish passage.

There are an estimated 10,000 dams and weirs installed in the Murray-Darling Basin (MDB). Two major weir designs, undershot and overshot, are constructed on MDB waterways, both delivering water downstream in a different way. Overshot weirs deliver water in a water-fall effect, and undershot weirs release water from under a sluice gate.  A controlled field study aimed to determine the impacts of both weir designs on downstream fish passage of common MDB fish species at a range of flows to determine fish welfare impacts.

Passage through overshot weirs was associated with substantially greater survival in all species compared to undershot weirs.  Few fish died, and the main welfare issues arose when water from overshot weirs fell into shallow water, causing fish to become physically injured when impacting the downstream weir apron.  These results indicate that the construction of overshot weirs with deep plunge pools would provide safe conditions for many fish species and sizes moving downstream.

In contrast, most Golden perch (Maquaria ambigua) and Silver perch (Bidyanus bidyanus) larvae, and more than half of Murray cod (Maccullochella peelii) larvae died during undershot weir passage, regardless of tailwater depth.  Small-bodied native fish such as Australian smelt (Retropinna semoni) and Unspecked hardyhead (Craterocephalus stercusmuscarum) displayed extremely high mortality when passing through undershot weirs.

Adult life stages of large-bodied species were also affected by undershot weirs but to a much lesser degree, with most adult Golden perch and Silver perch and a third of Murray cod suffering minor injuries when passing through small gate openings.  Analysis determined that undershot weirs were characterised by higher values of shear, turbulence and pressure changes.  Modifications were made to undershot gates to try and reduce these impacts, but unfortunately none of the trials successfully mitigated effects on native fish.

The findings of this study are particularly relevant for the MDB, given that over 80% of main channel weirs in most inland rivers now use undershot weirs.  Continuing upgrades to undershot weir structures in smaller creeks and tributaries will certainly improve water delivery efficiency, but may substantially increase incidences of injury and mortality of native fish over a large spatial scale.

Options to design and fit undershot weirs with ‘fish friendly’ flow modifications should be explored to minimise these threats to native fish.  Alternatively, assessing the applicability of stationary screens may represent a useful method for preventing fish entrainment and subsequent injuries. It is important that any such structure could protect all life history stages and have applicability over a large spatial scale. These should be seen as a priority area for future native fish management work.

Full report here: Baumgartner, L., McPherson, B., Doyle, J., Cory, F., Cinotti, N. and Hutchison, J. 2010. Quantifying and mitigating the impacts of weirs on downstream passage of native fish in the Murray-Darling Basin. NSW Department of Industry and Investment, Narrandera.

Full Text Available Broad-crested side weirs have been the subject of numerous hydraulic studies; however, the flow field at the weir crest and in front of the weir in the approach channel still has not been fully described. Also, the discharge coefficient of broad-crested side weirs, whether slightly inclined towards the stream or lateral, still has yet to be clearly determined. Experimental research was carried out to describe the flow characteristics at low Froude numbers in the approach flow channel for various combinations of in- and overflow discharges. Three side weir types with different oblique angles were studied. Their flow characteristics and discharge coefficients were analyzed and assessed based on the results obtained from extensive measurements performed on a hydraulic model. The empirical relation between the angle of side weir obliqueness, Froude numbers in the up- and downstream channels, and the coefficient of obliqueness was derived.

Full Text Available The paper deals with research focused on description of flow structure in front of broad-crested weir. Based on experimental measurement, the flow structure in front of the weir (the recirculation zone of flow and tornado vortices and flow structure on the weir crest has been described. The determined flow character has been simulated using numerical model and based on comparing results the suitable model of turbulence has been recommended.

Vital for water management are structures that can measure the flow in a wide variety of channels. Chapter 1 introduces the long-throated flume and the broad-crested weir; it explains why this family of structures can meet the boundary conditions and hydraulic demands of most measuring

his paper is concerned with the determination of the relationship for the calculation of the discharge coefficient at free overflow over a rectangular sharp-edged broad-crested weir without lateral contraction. The determination was made on the basis of new measurement in a range of the relative thickness of the weir from 0.12 to 0.30 and newly in a large range of relative height of the weir extremely from 0.24 to 6.8 which greatly expands the application possibilities of low weirs. In additi...

Full Text Available This paper is concerned with the determination of the relationship for the calculation of the discharge coefficient at free overflow over a rectangular sharp-edged broad-crested weir without lateral contraction. The determination was made on the basis of new measurement in a range of the relative thickness of the weir from 0.12 to 0.30 and newly in a large range of relative height of the weir extremely from 0.24 to 6.8 which greatly expands the application possibilities of low weirs. In addition, the effects of friction and surface tension on the value of the discharge coefficient were evaluated as well as the effect of the relative thickness of the weir. The new equation for discharge coefficient, expressed using the relative height of the weir, was subjected to verification made by an independent laboratory which confirmed its accuracy.

The most common types of weirs are the broad-crested weir, the sharp-crested weir, the circular crested weir and the ogee crested weir. Advantages of the cylindrical weir shape include the stable overflow pattern, the ease to pass floating debris, the simplicity of design compared to ogee crest design and the associated lower costs. In present study, it was investigated the overflow characteristics of circular weirs in laboratory for various cylinder radii of three sizes (11.4, 9.0, 6.3 cm), ...

Full Text Available The most common types of weirs are the broad-crested weir, the sharp-crested weir, the circular crested weir and the ogee crested weir. Advantages of the cylindrical weir shape include the stable overflow pattern, the ease to pass floating debris, the simplicity of design compared to ogee crest design and the associated lower costs. In present study, it was investigated the overflow characteristics of circular weirs in laboratory for various cylinder radii of three sizes (11.4, 9.0, 6.3 cm, and the models fixed on the channel bed vertically to the direction of flow. The result shows that the increase in the ratio of head to weir radius ratio (Hw/R value causes an increase in discharge coefficient (Cd value for the same height of weir. It was observed that the cylinder size (i.e. radius of cylindrical weir (R has an effect on the (Cd. The flow magnification factor (qw/qs increases with an increase in (Hw/R value and values of (qw/qs were always higher than one for all values of (Hw/R, this means that weirs of cylindrical shape performed better than those of sharp crest for any value of weir radius tested in this study.

sharp - crested weir , it is between 0.55 and 0.58, and a broad - crested ...implementation, different weir coefficients are specified for the weir structure design, sharp - crested or broad - crested weir . The lowest value in the...coefficient range is used for the sharp - crested (0.55) and broad - crested (0.46) weir , respectively; the flux comparison between these two

This paper presents the results of a laboratory study on the flow characteristics of sharp-crested weirs, broad-crested weirs, and labyrinth weirs. The variation of the maximum bubble penetration depth for different weir types is investigated depending on overfall jet expansion, discharge, and drop height. Moreover, most efficient depth, length and width of the downstream receiving pool in an open channel system are studied by considering the penetration depth, overfall jet expansion, jet tra...

Full Text Available Rectangular short-crested weirs are widely used for simple structure and high discharge capacity. As one of the most important and influential factors of discharge capacity, side slope can improve the hydraulic characteristics of weirs at special conditions. In order to systemically study the effects of upstream and downstream slope coefficients S1 and S2 on overflow discharge coefficient in a rectangular short-crested weir the Volume of Fluid (VOF method and the Renormalization Group (RNG κ-ε turbulence model are used. In this study, the slope coefficient ranges from V to 3H:1V and each model corresponds to five total energy heads of H0 ranging from 8.0 to 24.0 cm. Comparisons of discharge coefficients and free surface profiles between simulated and laboratory results display a good agreement. The simulated results show that the difference of discharge coefficients will decrease with upstream slopes and increase with downstream slopes as H0 increases. For a given H0, the discharge coefficient has a convex parabolic relation with S1 and a piecewise linearity relation with S2. The maximum discharge coefficient is always obtained at S2 = 0.8. There exists a difference between upstream and downstream slope coefficients in the influence range of free surface curvatures. Furthermore, a proposed discharge coefficient equation by nonlinear regression is a function of upstream and downstream slope coefficients.

This paper presents the applications of a newly developed free surface flow model to the practical, while challenging overflow problems for weirs. Since the model takes advantage of the strengths of both the level set and volume of fluid methods and solves the Navier-Stokes equations on an unstructured mesh, it is capable of resolving the time evolution of very complex vortical motions, air entrainment and pressure variations due to violent deformations following overflow of the weir crest. In the present study, two different types of vertical weir, namely broad-crested and sharp-crested, are considered for validation purposes. The calculated overflow parameters such as pressure head distributions, velocity distributions, and water surface profiles are compared against experimental data as well as numerical results available in literature. A very good quantitative agreement has been obtained. The numerical model, thus, offers a good alternative to traditional experimental methods in the study of weir problems.

This paper reports on laboratory research on the sediment passage capability through long-throated flumes and broad-crested weirs with which the Froude number in the approach channel does not exceed 0.6 over a distance of about 20 times the water depth upstream of the structure. Design rules are

Side weirs are flow diversion or intake devices that are widely used in irrigation and drainage networks and urban sewage systems. Labyrinth weirs have a proven hydraulic advantage due to their increased discharge rate at the same head for a given design condition. A labyrinth weir is defined as a weir crest that is not ...

broad - crested weir equation and the sharp crested circular... weir equation. Broad - crested weir equation: Q = CLH 1 .5 (C = varies, L = varies, H is the head on weir ). Circular weir equation: Q = C0 2rR (H0 )5 (C0...the toe of the downstream embankment. The spillway inlet is about 25 feet upstream of the crest of the dam. (3) Pertinent physical data are given

than broad - crested - weir coefficients. h. Available data on the effects of submerg nce on discharge coef- ficients for both sharp - and broad - crested ...flow over a broad - crested weir . The equation for free J discharge is: Q = Cf - 2 KH) 3/2 where Cf is an empirical coefficient, L is the length of...0,10 for square-end contractions. The free-flow coefficient Cf varies with the ratio of head H to width B of the broad - crested weir in the direction of

Broad Crested Weir 0.70 to 0.90 Sharp Crested Weir with Straight Slope Face 1.05 Sharp Crested Weir with Vertical Face 0.80 Sluice Gates with...Reaeration by turbulent flow over a dam Reaeration will occur when water falls over a dam, weir , or other structure in the stream. The amount of reaeration...Goulding. 1995. Phosphorus leaching from soils containing different phosphorus concentrations in the Broad - balk experiment. J. Environ. Qual. 24:904–910

Free crest spillways are hydraulically efficient and safe in operation. Since their discharge capacity is directly proportional to the crest length several types have been developed with the purpose to increase the length of the latter. Among these types traditional labyrinth weir spillways have been studied and used for a long time. Their hydraulic performance and the effect of the involved geometrical parameters are well known. Nevertheless, their design still has to be based on experiment...

This chapter describes procedures for measuring peak discharges using dams, weirs, and embankments. Field and office procedures limited to this method are described. Discharge coefficients and formulas are given for three general classes of weirs-sharp-crested, broad-crested, and round-crested-and for highway embankments and weirs of unusual shape. The effects of submergence are defined for most forms.

The gated weir is a weir that the crest elevation could be operated based on the flow through the river. The upstream water level of the gated weir could be controlled with gate opening or closing. This study applied a simulation with HEC-RAS 4,0 program in order to know the river hydraulic condition after the gated weir has built. According to the rainfall intensity from each sub-watershed, Distribution Log Pearson III with return period 50 years (Q50) was determined to calculate the design flood discharge. By using Rational Method, the design flood discharge is 470 m3/s. The Results show that capacity of the river is able to accomodate Q50 with discharge 470 m3/s and the gate should be fully opened during flood. This condition could passed the normal discharge at + 5.00 m elevation.

Full Text Available Introduction: Pivot weirs (sharp crested inclined weirs, Fig. 1-a is frequently used for discharge measurement, controlling water surface and flow diversion. Some typical features of pivot weirs are: (a overshot design for better water level control, (b Their application as head gates, turnout or check structure which requiring low head loss and high accuracy, (c ease of removing sediment deposit behind the weir, and (d ability to manage and monitor on-site or operating remotely when connected to a supervisory control and data acquisition (SCADA network. Kindsvater and Carter (8 derived a weir discharge equation based on energy and continuity equations. Hulsing (4 determined head-discharge relationship of inclined suppressed sharp crested weir with the slope of 3:3, 2:3 and 1:3 toward downstream and compared them with the equivalent normal sharp crested weir. In the USBR report on pivot weirs (regarding The Boulder Canyon Project,1948 the head discharge data of the suppressed pivot weir were presented in a channel with 5.5m length, 2.9m depth and 0.61m width. Some field experiments were also carried out in the IID (Imperial Irrigation District on a trapezoidal cross-section (0.61 m bottom width channel with pivot weir of 1.7m length, and two different widths of 1.63m. The flow rate (350-880 lit/s was held constant and different angles (15-50° calibrated instead of holding the angle constant and varying the flow rate. Some other laboratory tests were performed with Wahlin and Replogle (1994 on two pivot weirs with 1.2 m and 1.14 m width for the 0.61 m and 0.46 m length of blade and contraction factor of 0.925. RUBICON Company established an extensive operation on the application and automation of pivot weirs in irrigation channels in Australia (Www.rubicon.com. All previous studies concentrated on modifying the normal rectangular weir head-discharge equation so that it can be used for the pivot weirs. In this study, it is trying to derive a

service spillway was analyzed as a sharp - crested weir with:.a discharge coefficient (c) of 3.1. The auxiliary spillway channel was analyzed as a broad ...upstream portion of this channel is a concrete structure which forms a 27.4 foot long rectangular weir . There is a 5 foot vertical drop beyond the crest ...I on 1.5 Crest Width (ft) 12 g. Service Spillway Type: Concrete channel-rectangular weir . Five foot vertical drop beyond crest . Masonry and laid up

in good agreement with other broad - and sharp - crested weirs . 19. Early testing of the typical type I structure indicated that the size of the riprap...III structure (Figure 4) will consist of a concrete weir with a crest lo- cated 10.0 ft above the channel bottom with a 1-ft-high end sill at the end...to the channel, was effective in preventing significant head differ- ential and damage to the strucLure with overbank flow conditions. The weir crest

0.6. The two gravity sections were analyzed as sharp - crested weirs with a C of 3.2. For water surface elevations rising above the top-of-dam...elevation, a broad - crested weir C of 2.63 was used. Although there exists a small water-control structure at a bridge 200 feet left of the spiliway’s left...operating service I/ M/A Chute Length __ _ _ 7t± Height Between Spillway Crest IA & Approach Channel Invert ( Weir Flow) :5 50I1A. GqA1ES @ AJ I - CO

For horizontal flow, a sharp crested lip is generally most affected by submergence, whereas a broad crested weir is least affected by submergence...of an outer flume that was the sump for the pump and an inner flume that had a sharp - crested weir at the downstream end that was used for flow...backwall location, the floor at el 11.5, the el 16 sharp crested lip, and the reduced flare angle of the flowerpot section. The piers were added to

Topographical restraints for design storm flow are described as sharp-crested weirs for low flows in series with broad-crested weirs for the high flows. These design selections are considered to be most economical while providing the specified flow measuring capabilities for movement of radionuclides from the solid waste disposal areas into the surface streams around ORNL

In this paper two different reregulation weir designs for dam release improvement are discussed. A porous timber crib is favored for applications where increased minimum flow is needed, and a labyrinth with vertical walls is favored where both minimum flow and aeration are needed. Weirs constructed below hydropower dams can improve minimum flows between generating periods and increase tailwater dissolved oxygen (DO) content during generation. TVA has developed two distinct functional designs: a timber crib weir for minimum flow and a labyrinth weir for minimum flow and aeration. A target minimum flow is sustained by slow drainage of the weir pool between periodic refills. With the labyrinth weir, aeration occurs during generation via overtopping. Both weirs are designed to maximize the value of the tailwater while minimizing backwater on the upstream turbine, unsafe hydraulic conditions, and environmental disturbance

This report describes a study of dam passage and survival of radio-tagged juvenile salmonids after installation of a temporary spillway weir (TSW) at Little Goose Dam, Washington, in 2009. The purpose of the study was to document fish passage and survival when the dam was operated with the TSW in place. Spillway weirs are one of several methods used to improve downstream passage of juvenile salmonids. Each spillway weir design is based on the concept of providing an overflow weir with a depth more similar to the natural migration depth of juvenile salmonids than conventional spill bays. Little Goose Dam was the last of the four lower Snake River dams to have a spillway weir installed. This was the first year that some form of surface passage device was operating at all Snake River and Columbia River dams between Lewiston, Idaho, and the Columbia River estuary. The study design stipulated that a total of 30 percent of the river discharge would continuously be passed over the TSW and the conventional spill bays, and this percentage was achieved. The TSW also was to be operated at the "low crest" elevation during the spring and the "high crest" elevation during the summer, but the TSW was only operated at the low crest elevation during this study. Behavior, passage, and survival of spring and summer juvenile salmonid migrants passing through Little Goose Dam were examined using radio telemetry. Survival was estimated using the Route Specific Survival Model (RSSM) by releasing tagged fish near Central Ferry State Park 21 kilometers upstream of the dam and in the tailrace approximately 0.5 kilometer downstream of the dam. From April 18 to May 21, 2009, 1,520 yearling Chinook salmon (Oncorhynchus tshawytscha) and 1,517 juvenile steelhead (O. mykiss) were radio tagged and released. From June 6 to July 5, 2009, 4,251 subyearling Chinook salmon (O. tshawytscha) were radio tagged and released. Release dates of subyearling Chinook salmon were selected to avoid "reservoir

Alberta Environment"s water management operations (WMO) own and operates 46 dams and 800 km of canals. This presentation discussed a rehabilitation program designed to improve the safety of the WMO"s Calgary weir which was built in 1908 to encourage settlement in the province. The weir includes a 32 m wide sluiceway, a 2.5 m concrete weir, and a fish ladder. A portage trail has been built to accommodate canoes, and signs are posted to indicate the hazards associated with the weir. The WMO has also launched an advertising campaign to outline hazards to the general public. The WMO has a contract with the Calgary fire department (CFD) to maintain a safety boom and provide rescue operations at the weir. The weir project aims to accommodate access and safety while enhancing flood conveyance capabilities of the weir. The project will allow upstream passage for patrol boats operated by the Calgary fire department"s aquatic rescue service. The final design of the weir will include a series of drops constructed downstream of the weir to create pool and riffle structures that will eliminate hydraulic rollers. Notches will be cut in the weir to regulate flows moving through the new low and high flow channels. Case studies of other low-head dams operated by the WMO were also presented. tabs., figs.

Alberta Environment Water Management Operations (WMO) owns and operates 46 dams and 800 kilometres of canals in Alberta. The WMO consists of 120 staff and several contract operators to take care of this infrastructure. Most of the infrastructure supplies water for irrigation use, which adds 5 billion dollars to the provincial economy annually. Other water uses include stock watering, domestic use, municipal use, recreational use and habitat. Alberta Environment"s weir safety program was also discussed along with options for rehabilitation to improve public safety. A case study of Calgary"s Weir Dam on the Bow River was highlighted. A brief history of the dam was offered and safety programs around provincially-owned weirs were discussed. Photographs were included to illustrate some of the additional safety measures at the Calgary weir, such as suspended safety buoys upstream of the boom directing paddlers to the portage trail, and signage on the river that can be activated when the boom is out. Typical river users on the Calgary Bow River and safety history at the Calgary Weir were discussed along with other topics such as the Calgary Bow River weir project criteria; project design progress; pre-feasibility options; scale modelling; final design analysis; construction funding; and proposed changes to the safety program for the new weir configuration. figs.

Alberta Environment Water Management Operations (WMO) owns and operates 46 dams and 800 kilometres of canals in Alberta. The WMO consists of 120 staff and several contract operators to take care of this infrastructure. Most of the infrastructure supplies water for irrigation use, which adds 5 billion dollars to the provincial economy annually. Other water uses include stock watering, domestic use, municipal use, recreational use and habitat. Alberta Environment"s weir safety program was also discussed along with options for rehabilitation to improve public safety. A case study of Calgary"s Weir Dam on the Bow River was highlighted. A brief history of the dam was offered and safety programs around provincially-owned weirs were discussed. Photographs were included to illustrate some of the additional safety measures at the Calgary weir, such as suspended safety buoys upstream of the boom directing paddlers to the portage trail, and signage on the river that can be activated when the boom is out. Typical river users on the Calgary Bow River and safety history at the Calgary Weir were discussed along with other topics such as the Calgary Bow River weir project criteria; project design progress; pre-feasibility options; scale modelling; final design analysis; construction funding; and proposed changes to the safety program for the new weir configuration. figs.

Full Text Available The location and design of weirs as part of water supply system on the Tsarev settlement and its neighborhood are considered in the article. The descriptions of the 19th – early 20th cc. and archaeological data made it possible to establish the fact that the weirs had been constructed of earth with a backfill made of stones, bricks and slag. They served to regulate water discharge and to construct reservoirs. On the basis of 19th-century topographic maps and satellite images, it has been possible to figure out the locations and purpose of four major weirs, which had occupied key positions both outside and inside the town. Two reservoirs were constructed to the west and east of the town by means of large weirs (over 200 m long and 10 m tall. Two lesser weirs used to form internal water reservoirs.

designed as a broad - crested weir to pass the maximum probable flood (PF) with a peak of 24,500 ofs. The spillway crest length of 100 feet and the...well as from the Miocene Topanga sandstone and the Modelo shale found near the crest of the Santa Susana Mountains in Aliso and Rice Canyons. Fossil...440 1.5 .IN THE AREA. 1I0.050: DRAINAGE AREA IS QUITE RUGGED, WITH SHARP RIDGES 4.4 600 1.3 .050 AND NARROW, STEEP CANYONS THROUGH WHICH WATERCOURSES

was simulated by means of a broad - crested weir built into the topography of the mesh. There is 0.5 m of freeboard and the width of the weir is 30 m...ER D C/ CH L TR -1 2- 5 Camp Marmal Flood Study Co as ta l a nd H yd ra ul ic s La bo ra to ry Jeremy A. Sharp , Steve H. Scott...Camp Marmal Flood Study Jeremy A. Sharp , Steve H. Scott, Mark R. Jourdan, and Gaurav Savant Coastal and Hydraulics Laboratory U.S. Army Engineer

Restoration projects are often implemented to address specific issues in the environment. Consequences of a restoration project, if any are measured, typically focus on direct changes to the projects focus. However, changing habitat structure likely results in changes to the environment that affect the communities living there. Rock weirs have been used for channel stabilization in many midwestern rivers. Previous research in a southern Illinois river found that weirs benefitted aquatic macroinvertebrate and riparian bird communities by enhancing habitat heterogeneity and insect emergence production. We hypothesized that fishes would also benefit from weirs through enhanced habitat and food availability. We collected fishes in the Cache River in southern Illinois using hand nets, seines, and electroshocking at sites where weirs had been installed and at non-weir sites. Gut contents were identified and individual food items measured. Fish species richness, but not diversity, was higher at weir sites. Fish communities also differed between site types, with benthic feeders characterizing weir sites. Gut content biomass and abundance differed among fish guilds but not between weir and non-weir sites. Fishes from both site types selected for prey taxa predominately found at weirs. Differences between site types were not always captured by univariate metrics, but connecting fish prey to habitat suggests a reach-scale benefit for fishes through increased abundance of favored prey and enhanced prey diversity. Additionally, given the paucity of rocky substrata in the river as a whole, rock weirs enhance fish species richness by providing habitat for less common benthic species.

would cause overtopping of the embankment, which would act as a broad - crested weir . The proposed Harlow Road embankmert section would act as a critical...runoff from the 8 inches of snow covering the area. The creek crested at 5:00 a.m. on March 31, at 8.99 feet, which is the maximum stage of record at...gradual convergence to a maximum of 0.7 __ for a sharp divergence. Bridge losses have been computed from the formula for restricted openings: Q = KA(2gh+V2

Full Text Available The development of laser-scan techniques provides opportunity for detailed terrain analysis in hydrologic studies. Ground based scans were used to model the ground surface elevation in the area of a stream gauge weir over an area of 240 m2 at a resolution of 0.05 m. The terrain model was used to assess the possibility of flow bypassing the weir and to calculate stream flow during filling of the weir pool, prior to flow through the weir notch. The mapped surface shows a subtle low-lying area at the south end of the structure where flow could bypass the weir. The flow calculations quantify low-flows that do not reach the weir notch during small rain events and flow at the beginning of larger events in the ephemeral stream.

Spent fuel pool is crucial facility for fuel storage and nuclear safety, and the spent fuel pool weir gate is the key related equipment. In order to achieve a goal of more efficient driving force transfer, loading during the opening/closing process is analyzed and an optimized calculation method for dimensions of driving mechanism is proposed. The result of optimizing example shows that the method can be applied to weir gates" design with similar driving mechanism.

The Four Major Rivers Restoration Project was conducted to secure sufficient water resources, introduce comprehensive flood control measures, and improve water quality while restore the river ecosystem in Korea. The dredging of river bed and the installation of 16 weirs were done in Han, Geum, Yeongsan, and Nakdong rivers from late 2010 to early 2012 as a part of the project. Groundwater data obtained from 213 groundwater monitoring wells near the four major rivers were used to analyze the impacts of weir construction on the nearby groundwater flow system. The groundwater level and chemical characteristics were analyzed to investigate how the groundwater flow system and water quality changed after the weir construction. The results showed that groundwater level rose immediately following the rise of stream stage after the weir construction. Also, the hydrologic condition of the stream in some upland of the weirs was changed from a gaining to a losing stream. Consequently, the direction of groundwater flow was changed from perpendicular to parallel to the stream, and it swapped the groundwater in the downstream of the weir for the water recharged from the stream. Considering the results, some groundwater quality is expected to be changed and become similar to that of the stream, although the change has been not observed yet. Therefore, both further monitoring of the groundwater quality and hydrogeochemical analysis are required for quantitatively evaluating the effect of the weir.

Full Text Available Introduction: Flow patterns within the river bend is three dimensional. Occurrence of secondary flow due to centrifugal force and formation of helicoidally vortex in river bend usually causes the outer bank of river erodes whilst the sediment are deposited in inner bend which appears in the form of point bars. To reduce the river bank scour, many techniques have been developed which may be classified as covering technique and modified flow patterns methods. The W-weir is among such structures. In the present paper, by measuring three components of flow velocity with and without presence of W-weir, variation of flow patterns and shear stress distribution in a 90-degree sharp bend have been investigated. The main purpose of this study is to see the installation of different locations of W-weir in the bend on reduction of outer bank scour. In the present paper, by measuring three components of flow velocity with and without presence of W-weir, variation of flow patterns and shear stress distribution in a 90-degree sharp bend have been investigated. The analyses of data showed more uniform flow upstream of the weir and also revealed that the effect of transverse and centrifugal forces are modified in such a way that the secondary flow is diminished. The results showed that for 30, 60 and 90-degree bends maximum erosion depth in the vicinity of the outer bank with Froude number of 0.206 in comparison with 0.137 has increased up to 84, 90 and 118 % respectively. In both Froude numbers, installation of W-Weir in 30 degree has the most reduction in bed in comparison with 60 and 90 degree. Materials and Methods: To reach the goal of this study a physical model of 90 degree sharp bend was constructed in the hydraulic lab of Shahid Chamran university of Ahvaz. The ratio of R(radius/b(flume width was less than 2 which shows a sharp bend. The W-weir was built with 1mm galvanized steel. Flume bed was covered with sediment of D50=1.5mm. The W-weir was

In a FBR, the inside of the reactor vessel is cooled by liquid sodium. Liquid sodium is supplied to the upper plenum from its bottom and discharges over the top of the cylindrical weir down to the lower plenum. The weir is so thin in order to decrease the thermal stress on it that the fluid--structure interaction becomes predominant. A fluidelastic vibration of the weir due to fluid discharge was discovered in a French FBR. In this study, a theoretical model was developed on the ""fluid--elastic mode"" instability of a cylindrical weir due to fluid discharge from the upper plenum to the lower plenum. In the analysis, the fluctuation of both the discharge flow rate over a weir due to the vibration of the cylindrical shell and the pressure in the lower plenum due to fluid discharge were formulated. Instability criteria was derived from the added damping ratio due to fluid discharge using modal analysis. The natural modes and modal mass of the weir were obtained by the analysis using the FEM code taking the fluid - structure interaction into consideration. The theoretical instability range in terms of the fall height and the flow rate is compared with the experimental results. The theoretical values showed a good agreement with the experimental ones

An analytical model for the fluid-elastic instability as observed in Super-Phenix-1 LMFBR is proposed. This fluid-structure system is constituted by the flexible weir and adjoining fluid plenums, and the fluid is discharged from the upstream plenum to the downstream plenum over a flexible weir. The characteristic equation of the system is derived for the case in which the weir vibrates at the frequency of the downstream plenum sloshing. The effects of the fluid level difference between the upstream and the downstream plenum and weir rigidity are examined, and the mechanism for instability is discussed. (author)

This interim report for the Swiss Federal Office of Energy (SFOE) takes a look at a small hydro scheme in Muellheim, Switzerland. An existing weir that provides water for two small hydropower stations is to be augmented with a new installation at the weir. Three possible variants for the project are described and discussed. The topology, geology and hydrology of the location are examined. The project also involves a higher weir and the provision of a fish pass. Special consideration concerning the stability of a railway bridge just above the new weir is noted. The organisation of the building site and the six phases of the works to be carried out are discussed. The installation of two turbines is noted and their proposed energy production is commented on.

We used pre- and post-restoration channel surveys of the Donner und Blitzen River, Oregon, to evaluate the effects of grade-control structures on channel morphology and baseflow habitat conditions for native redband trout and other aquatic biota. Six years after installation, we found that the channel had a smaller proportion of riffles and pools and less gravel substrate, combined with an increase in the proportion of flat waters and consolidated clay on the bed surface. Both local scour downstream from weirs and backwater effects upstream from weirs appear to have caused the general flattening and fining of the channel. A direct-step backwater calculation indicates that backwaters extended to the upstream weir at both low and high flows, creating long sections of flat water separated by short, steep drops. Despite backwater effects, a comparison of longitudinal profiles before and six years after weir installation showed bed erosion downstream of nearly all weirs, likely a consequence of the cohesive clay material that dominates the channel bed and banks. A deep inner channel reflects the cohesive nature of the clay and the mechanisms of abrasion, and indicates that sediment load is low relative to the transport capacity of the flow. Unfortunately, weirs were problematic in this system because of the cohesive clay substrate, limited sediment supply, and low channel gradient. Although deeper flows due to backwaters might be more favorable for resident trout, less gravel and fewer riffles are likely to negatively impact trout spawning habitat, macroinvertebrate communities, and biofilm productivity. Our results demonstrate the potential limitations of a single-feature approach to restoration that may be ineffective for a given geomorphic context and may overlook other aspects of the ecosystem. We highlight the need to incorporate geomorphic characteristics of a system into project design and predictions of system response. Copyright © 2012 Elsevier Ltd. All rights

In many hydraulic structures, side weirs have a critical role. Accurately predicting the discharge coefficient is one of the most important stages in the side weir design process. In the present paper, a new high efficient side weir is investigated. To simulate the discharge coefficient of these side weirs, three novel soft computing methods are used. The process includes modeling the discharge coefficient with the hybrid Adaptive Neuro-Fuzzy Interface System (ANFIS) and three optimization algorithms, namely Differential Evaluation (ANFIS-DE), Genetic Algorithm (ANFIS-GA) and Particle Swarm Optimization (ANFIS-PSO). In addition, sensitivity analysis is done to find the most efficient input variables for modeling the discharge coefficient of these types of side weirs. According to the results, the ANFIS method has higher performance when using simpler input variables. In addition, the ANFIS-DE with RMSE of 0.077 has higher performance than the ANFIS-GA and ANFIS-PSO methods with RMSE of 0.079 and 0.096, respectively.

Full Text Available Multifunctional weirs can be used to maintain water supply during dry seasons and to improve downstream water quality during drought conditions through discharge based on retained flux. Sixteen multifunctional weirs were recently constructed in four river systems as part of the Four Rivers Restoration Project. In this study, three multifunctional weirs in the Geum River Basin were investigated to analyze the environmental effects of multifunctional weir operation on downstream flow. To determine seasonal vulnerability to drought, the basin was evaluated using the Palmer Drought Severity Index (PDSI. Furthermore, the downstream flow regime and the effect on water quality improvement of a coordinated dam–multifunctional weir operation controlled by: (a a rainfall–runoff model; (b a reservoir optimization model; and (c a water quality model, were examined. A runoff estimate at each major location in the Geum River Basin was performed using the water quality model, and examined variation in downstream water quality depending on the operational scenario of each irrigation facility such as dams and weirs. Although the water quality was improved by the coordinated operation of the dams and weirs, when the discharged water quality is poor, the downstream water quality is not improved. Therefore, it is necessary to first improve the discharged water quality on the lower Geum River. Improvement of the water quality of main stream in the Geum River is important, but water quality from tributaries should also be improved. By applying the estimated runoff data to the reservoir optimization model, these scenarios will be utilized as basic parameters for assessing the optimal operation of the river.

A new type fluidelastic instability was discovered during the hot tests of Superphenix LMFBR. This instability is due to the fluid discharge, over a flexible weir shell which separates two of these fluid sheets (the feeding and restitution collectors). An analytical nonlinear model was realised. The flow and force sources at the top of the collectors are described and projected on the modal basis of the system formed by the collectors and the weir shell. Simplified formulas were extracted allowing a practical prediction of the stability. More generally, the complete model can be used to estimate the vibratory level when a steady state is reached by the effect of nonlinearities. Computer calculation for such a model are made with OSCAR code, part of CASTEM 2000 finite element computer system. (author)

This document presents the three dimensional computational modeling of a labyrinth weir, using the version 17.0 of the Computational Fluid Dynamics (CFD) software ANSYS - FLUENT. The computational characteristics of the model such as the geometry consideration, the mesh sensitivity, the numerical scheme, and the turbulence modeling parameters. The volume fraction of the water mixture - air, the velocity profile, the jet trajectory, the discharge coefficient and the velocity field are analyzed. With the purpose of evaluating the hydraulic behavior of the labyrinth weir of the Naveta"s hydroelectric, in Apulo - Cundinamarca, was development a 1:21 scale model of the original structure, which was tested in the laboratory of the hydraulic studies in the Escuela Colombiana de Ingeniería Julio Garavito. The scale model of the structure was initially developed to determine the variability of the discharge coefficient with respect to the flow rate and their influence on the water level. It was elaborate because the original weir (labyrinth weir with not symmetrical rectangular section), did not have the capacity to work with the design flow of 31 m3/s, because over 15 m3/s, there were overflows in the adduction channel. This variation of efficiency was due to the thickening of the lateral walls by structural requirements. During the physical modeling doing by Rodríguez, H. and Matamoros H. (2015) in the test channel, it was found that, with the increase in the width of the side walls, the discharge coefficient is reduced an average by 34%, generating an increase of the water level by 0.26 m above the structure. This document aims to develop a splicing methodology between the physical models of a labyrinth weir and numerical modeling, using concepts of computational fluid dynamics and finite volume theories. For this, was carried out a detailed analysis of the variations in the different directions of the main hydraulic variables involved in the behavior, such as, the

The excitation mechanism of a self-excited oscillation due to the fluid discharge over a flexible weir was investigated both theoretically and experimentally. A new type of hydroelastic instability was discovered during test operations of the Super-Phenix LMFBR reactor in France. According to the recent report by Aita, this phenomenon includes two types of instability modes: one is sloshing mode which means the oscillation of a weir associated with coupled sloshing modes of both feeding and restitution fluid collectors; the other is a hydroelastic mode which means the oscillation of a weir associated with fluid-shell modes. In this report, the excitation mechanism of a sloshing mode is discussed by calculating the excitation energy brought by discharge to the fluid-structure system. The theoretical results for the range of sloshing mode instability almost agreed with the experimental data. (author)

The excitation mechanism of a self-excited oscillation due to the fluid discharge over a flexible weir was investigated both theoretically and experimentally. A new type of hydroelastic instability was discovered during test operations of the Super-Phenix LMFBR reactor in France. According to a recent report by Aita, this phenomenon includes two types of instability modes: one is the sloshing mode which means the oscillation of a weir associated with coupled sloshing modes of both feeding and restitution fluid collectors; the other is a hydroelastic mode which means the oscillation of a weir associated with fluid-shell modes. In this report, the excitation mechanism of a hydroelastic mode is discussed by calculating the excitation energy brought by discharge to the fluid-structure system. The theoretical results for the range of hydroelastic mode instability virtually agreed with the experimental data. (author)

The purpose is to provide operation and maintenance, periodic inspection, and emergency action plans for White Oak Dam in general accordance with the Federal Emergency Management Agency (FEMA) guidelines for dam safety. It must be understood that operations at the site are primarily for purposes of environmental monitoring, environmental protection and waste management operations control. Effluent is generally allowed to flow from the lake at its natural rate by rising above the broad crested weir notch elevation of 744 feet m.s.l

Department of Water Resources Development and Management, Indian Institute ... on the hydrodynamic performance near inlet key of Piano Key Weir (PKW). ... nature of flows is clearly understood with the help of advanced instrumentation.

The purpose of the installation of temporary weirs at NT-4 is to collect empirical surface water discharge data for the tributary during baseflow conditions and following rainfall events, during the spring and summer of 1997 in support of the Department of Energy"s (DOE"s) Oak Ridge Reservation Waste Management Alternatives Evaluation project. The duration of surface-water monitoring activities is not planned to exceed 6 months. A minimum of four temporary weirs will be installed along the length of NT-4 in the locations indicated on Attachment A. The design specifications and locations for the weirs will be provided by the DOE prime contractor for the Oak Ridge Reservation Waste Management Alternatives Evaluation project. The weirs will be fabricated by the Y-12 labor forces of Lockheed Martin Energy Systems (LMES). The Environmental Compliance Organization (ECO) of LMES will perform data collection in addition to weir installation, inspection, maintenance, and removal. Flow meters that collect data at five minute intervals will be installed on each weir and visual measurements using staff gauges mounted on each weir will also be performed

Full Text Available The effects of weirs on fish and other biological communities have garnered considerable study, whereas the effects of weirs on community composition of toxic cyanobacteria have not yet been well documented. In this study, temporal and spatial variations in species composition and the abundance of potentially toxic cyanobacteria were investigated in the riverine regions of the temperate Youngsan River estuary, where two weirs have recently been constructed. Four stations were sampled 0.5 m below the surface monthly along the channel of the upper river from May 2014 to April 2015 to explore cyanobacterial composition and abundance, while physicochemical and biological parameters were measured to elucidate possible mechanisms controlling these dynamics. Two stations were located upstream at free-flowing sites, and the other stations were located downstream at impounded sites near the weirs. Twenty-eight cyanobacterial species were identified, seven of which were potentially toxic: Microcystis sp., M. aeruginosa, M. flos-aquae, Dolichospermum sp., Aphanocapsa sp., Oscillatoria sp. and Phormidium sp. Microcystis sp. was the most abundant in June 2014 at the lowest station near the weir. Meanwhile, Phormidium sp. occurred at low abundance throughout the study period, except during the winter months, when its abundance was elevated. The interactive forward selection method highlighted dissolved inorganic nitrogen and zooplankton abundance as explanatory variables for this observed variation, but their effects on cyanobacterial growth are unclear. However, temperature was the major determinant for the temporal variation in cyanobacterial populations. Cluster analysis showed that the downstream stations near the weirs had a high similarity of potentially toxic cyanobacteria. Significantly higher abundance, especially of Microcystis sp., was also recorded at the impounded sites suggesting that the presence of weirs might affect variations in toxic

Recent efforts to advance river connectivity for the Millstone River watershed in New Jersey have led to the evaluation of a low-flow gauging weir that spans the full width of the river. The methods and results of a desktop modelling exercise were used to evaluate the potential ability of three anadromous fish species (Alosa sapidissima [American shad], Alosa pseudoharengus [alewife], and Alosa aestivalis [blueback herring]) to pass upstream over the U.S. Geological Survey Blackwells Mills streamgage (01402000) and weir on the Millstone River, New Jersey, at various streamflows, and to estimate the probability that the weir will be passable during the spring migratory season. Based on data from daily fishway counts downstream from the Blackwells Mills streamgage and weir between 1996 and 2014, the general migratory period was defined as April 14 to May 28. Recorded water levels and flow data were used to theoretically estimate water depths and velocities over the weir, as well as flow exceedances occurring during the migratory period.Results indicate that the weir is a potential depth barrier to fish passage when streamflows are below 200 cubic feet per second using a 1-body-depth criterion for American shad (the largest fish among the target species). Streamflows in that range occur on average 35 percent of the time during the migratory period. An increase of the depth criterion to 2 body depths causes the weir to become a possible barrier to passage when flows are below 400 cubic feet per second. Streamflows in that range occur on average 73 percent of the time during the migration season. Average cross-sectional velocities at several points along the weir do not seem to be limiting to the fish migration, but maximum theoretical velocities estimated without friction loss over the face of the weir could be potentially limiting.

Collection of juvenile salmonids at Cowlitz Falls Dam is a critical part of the effort to restore salmon in the upper Cowlitz River because the majority of fish that are not collected at the dam pass downstream and enter a large reservoir where they become landlocked and lost to the anadromous fish population. However, the juvenile fish collection system at Cowlitz Falls Dam has failed to achieve annual collection goals since it first began operating in 1996. Since that time, numerous modifications to the fish collection system have been made and several prototype collection structures have been developed and tested, but these efforts have not substantially increased juvenile fish collection. Studies have shown that juvenile steelhead (Oncorhynchus mykiss), coho salmon (Oncorhynchus kisutch), and Chinook salmon (Oncorhynchus tshawytscha) tend to locate the collection entrances effectively, but many of these fish are not collected and eventually pass the dam through turbines or spillways. Tacoma Power developed a prototype weir box in 2009 to increase capture rates of juvenile salmonids at the collection entrances, and this device proved to be successful at retaining those fish that entered the weir. However, because of safety concerns at the dam, the weir box could not be deployed near a spillway gate where the prototype was tested, so the device was altered and re-deployed at a different location, where it was evaluated during 2013. The U.S. Geological Survey conducted an evaluation using radiotelemetry to monitor fish behavior near the weir box and collection flumes. The evaluation was conducted during April–June 2013. Juvenile steelhead and coho salmon (45 per species) were tagged with a radio transmitter and passive integrated transponder (PIT) tag, and released upstream of the dam. All tagged fish moved downstream and entered the forebay of Cowlitz Falls Dam. Median travel times from the release site to the forebay were 0.8 d for steelhead and 1.2 d for coho

Full Text Available In the process of calculating and simulating water discharge in free channels it is necessary to know the flow features in case of small values of Reynolds and Weber numbers. The article considers the influence of viscosity and surface tension on the coefficient of a weir flow with sharp threshold. In the article the technique of carrying out experiments is stated, the equation is presented, which considers the influence of all factors: pressure over a spillway threshold, threshold height over a course bottom, speed of liquid, liquid density, dynamic viscosity, superficial tension, gravity acceleration, unit discharge, the width of the course. The surface tension and liquid density for the applied liquids changed a little. In the rectangular tray (6000x100x200 spillway with a sharp threshold was established. It is shown that weir flow coefficient depends on Reynolds number (in case Re < ~ 2000 and Webers number. A generalized expression for determining weir flow coefficient considering the influence of the forces of viscosity and surface tension is received.

It is state of the art to evaluate and optimise sewer systems with urban drainage models. Since spill flow data is essential in the calibration process of conceptual models it is important to enhance the quality of such data. A wide spread approach is to calculate the spill flow volume by using standard weir equations together with measured water levels. However, these equations are only applicable to combined sewer overflow (CSO) structures, whose weir constructions correspond with the standard weir layout. The objective of this work is to outline an alternative approach to obtain spill flow discharge data based on measurements with a sonic depth finder. The idea is to determine the relation between water level and rate of spill flow by running a detailed 3D computational fluid dynamics (CFD) model. Two real world CSO structures have been chosen due to their complex structure, especially with respect to the weir construction. In a first step the simulation results were analysed to identify flow conditions for discrete steady states. It will be shown that the flow conditions in the CSO structure change after the spill flow pipe acts as a controlled outflow and therefore the spill flow discharge cannot be described with a standard weir equation. In a second step the CFD results will be used to derive rating curves which can be easily applied in everyday practice. Therefore the rating curves are developed on basis of the standard weir equation and the equation for orifice-type outlets. Because the intersection of both equations is not known, the coefficients of discharge are regressed from CFD simulation results. Furthermore, the regression of the CFD simulation results are compared with the one of the standard weir equation by using historic water levels and hydrographs generated with a hydrodynamic model. The uncertainties resulting of the wide spread use of the standard weir equation are demonstrated.

The exploitation of river systems for power and navigation has commonly been achieved through the installation of a variety of in-channel obstacles of which weirs in Britain are amongst the most common. In the UK, the historic value of many of these features is recognised by planning designations and protection more commonly associated with historic buildings and other major monuments. Their construction, particularly in the north and west of Britain, has often been associated with industries such as textiles, chemicals, and mining, which have polluted waterways with heavy metals and other contaminants. The construction of weirs altered local channel gradients resulting in sedimentation upstream with the potential as well for elevated levels of contamination in sediments deposited there. For centuries these weirs have remained largely undisturbed, but as a result of the growth in hydropower and the drive to improve water quality under the European Union"s Water Framework Directive, these structures are under increasing pressure to be modified or removed altogether. At present, weir modifications appear to be considered largely on an individual basis, with little focus on the wider impacts this might have on valley floor environments. Using a numerical modelling approach, this paper simulates the removal of major weirs along a 24-km stretch of the river Derwent, Derbyshire, UK, designated as a UNESCO World Heritage Site. The results suggest that although removal would not result in significant changes to the valley morphology, localised erosion would occur upstream of structures as the river readjusts its base level to new boundary conditions. Modelling indicates that sediment would also be evacuated away from the study area. In the context of the Derwent valley, this raises the potential for the remobilisation of contaminants (legacy sediments) within the wider floodplain system, which could have detrimental, long-term health and environmental implications for the

This study presents a novel 3-D hydrodynamic focusing technique for micro-flow cytometers. In the proposed approach, the sample stream is compressed initially in the horizontal direction by a set of sheath flows such that it is constrained to the central region of the microchannel and is then focused in the vertical direction by a second pair of sheath flows. Thereafter, the focused sample stream passes over a micro-weir structure positioned directly beneath an optical detection system to capture polystyrene beads fluorescent signal. The microchannel configuration and operational parameters are optimized by performing a series of numerical simulations. An experimental investigation is then performed using a micro-flow cytometer fabricated using conventional micro-electro-mechanical systems techniques and an isotropic wet etching method. The results indicate that the two sets of sheath flows successfully constrain the sample stream within a narrow, well-defined region of the microchannel. Furthermore, the mic