Showing papers on "Weir published in 2004"

Assessment of hydrologic alterations caused by chi-chi diversion weir in Chou-Shui Creek, Taiwan: Opportunities for restoring natural flow conditions

Abstract: The Range of Variability Approach (RVA) is used to investigate the hydrologic impacts of a diversion weir on Chou-Shui Creek, Taiwan. Thirty-two hydrologic parameters, called Indicators of Hydrologic Alteration (IHA), are used to evaluate the flow conditions before and after weir construction. One standard deviation from the mean for each of the pre-construction hydrologic parameters is set as the management target range. Under the prevailing diversion rules, large hydrologic alterations are observed, especially for low flows. The means of 19 hydrologic parameters presently fall outside of the targets and the average non-attainment rate for the 32 indicators is 73.2%. Increasing the instream flow release or reducing diversions could mitigate the hydrologic impacts of weir construction. Increasing the instream flow to 40 m3/s and reducing monthly water demands by variable percentages significantly improves the altered flow conditions. Under the proposed water release and diversion scheme, 29 hydrologic parameters will fall within the management targets and the average non-attainment rate will be reduced to 35.6%, much closer to the pre-construction value of 25.3%. Restoring the natural flow variability is expected to promote the natural stream biota. Copyright © 2004 John Wiley & Sons, Ltd.

Flow regimes and structure in pool and weir fishways

Abstract: The main objective of this work was to study the hydraulics of pool and weir fishways, for wider range of bed slopes, weir spacing, and heights, so that they can be designed to allow the passage of

Solvent extraction method and apparatus

Abstract: A weir assembly for use with a mixer-settler for liquid-liquid extraction includes in one embodiment an organic weir having an inlet opening below the free surface of the organic phase liquid and a vertically-adjustable front wall allowing adjustments in the position and/or height of the inlet opening. The organic weir can also feature an angled bottom coupled to a lip segment, an incline plate in the interior of the weir, and a front wall that is angled with respect to incoming fluid flow. In another embodiment the weir assembly can independently or additionally include an aqueous weir with a labyrinth section. The aqueous weir can optionally include an adjustable lip hingedly coupled to the top of the final partition in the labyrinth section.

Generalized Head-Discharge Equation for Flow over Sharp-Crested Inclined Inverted V-Notch Weir

Abstract: The sharp-crested weir is the most commonly used device in channels for flow measurement and flow regulation due to its simplicity. Attempts have been made to study in detail the flow over differen...

Slope stability analysis of potential bank failure as a result of toe erosion on weir-impounded lakes: an example from the Nepean River, New South Wales, Australia

Abstract: The consequences of weirs present on the Upper Nepean River on the long-term slope stability of both vegetated and devegetated riverbanks were investigated using models that account for the reinforcement of bank sediments by tree roots. The effects of the weirs in concert with channel widening and deepening caused by dredging in 1970s and 1980s, as well as natural processes, have turned the Upper Nepean from a small upland river into a series of quiet, narrow lakes, measuring 3–5 m deep, 30–70 m wide and several kilometres long. The surface of these lakes is located currently within the steep mid-bank zone. Wind-generated waves have eroded 1–3-m high scarps in the mid-bank region. These scarps are receding laterally at an average rate of 10 cm per year and this process is gradually undermining and destabilising the upper banks. In contrast, the mass of water impounded by the weirs currently acts to provide lateral support to the banks and improves their stability. Therefore, the existence of the weirs and their impounded lakes has currently both positive and negative effects on bank stability. The retention of the weirs will promote continued erosion at the waterline of the weir lakes that will eventually lead to the destabilisation and collapse of both vegetated and devegetated banks during future large floods. Demolition of the weirs would also lead to a renewed phase of bank failure during future floods as the stabilising effects of the weir lakes on the banks would be removed. The size of eventual failures will be larger and the distribution of such failures probably more widespread if the weirs are retained.

Experimental investigation of bed-load and suspended-load transport over weirs

Abstract: An experimental investigation was undertaken to model the transport of bed-load and suspended-load sediment over steep slopes such as dikes and weirs. Six tests were performed using a vertical wall weir and a sloped (1 : 4) wall weir. Measurements were made of bed-load and suspended-load transport rates upstream and downstream of the test section. It was found that upstream of a vertical weir a strong down-flow vortex forms. This vortex creates a scour hole at the base of the weir and entrains sediment entering the region so that all of the sediment is transported in suspension over the weir. Downstream of the weir a strong reverse vortex traps a proportion of the material in suspension and creates a deposition zone. The sediment supply and flow rate control the temporal development of this deposit. For a sloped weir the down-flow vortex is eliminated at the upstream weir face. However the strong acceleration of the flow moving up the slope is sufficient to entrain all of the bed-load material so again, a...

Vortex flow type water surface control device for drainage system

Abstract: In a conventional storm overflow chamber of a combined sewer system, inflowing floating debris do not flow into an intercepting pipe in a rainy weather, and flow out to a public water body, causing a water pollution in the public water body. According to a vortex flow type water surface control device for a draining device of the present invention, a control plate (6) higher than at least a separating weir (1) is provided between an opening of an inflow pipe (2) and an opening of an intercepting pipe (3) in a storm overflow chamber of a combined sewer system. Moreover, a guide wall (7) higher than at least the separating weir (1) is provided along the separating weir between the opening of the inflow pipe (2) and the separating weir (1).

Transition effects in flow over side weirs

Abstract: The effect of water surface slope in the lateral direction on flow over side weirs was studied. Water surface elevation on the weir plane was expressed by a parameter ψ based upon the hydraulic profile on the channel axis. Two different relationships of ψ as a function of the Froude number were used to calculate side weir discharges. Results were compared with the experimental data. It was shown that better results are obtained when transition conditions of ψ = 1 at the ends of the side weirs with no lateral surface slope are taken into account. However the effect of water surface slope in lateral direction is of secondary importance as compared to the angle of the deflected water jet along the side weir.

Supporting type labyrinth barrage

Abstract: The supporting labyrinth weir includes underplate and labyrinth weir walls, and features that in the upper part of two-to-two opposite weir walls, horizontal supporting beam is set and the outmost support beam is horizontal supporting beam or inclined supporting beam with upper end connected to the weir walls and the lower end to the underplate. Owing to the horizontal support beams in the equal distance and in the upper part of outside the weir walls, there are no cantilever beam stress state resulting in small size of weir wall and underplate cross section size, less reinforcing bars and low engineering cost.

New portable fishway design for existing trapezoidal weirs

Abstract: The improvement of the weir without a fishway is required in order that diadromous fishes, shrimps, and crabs can migrate to their upstream and downstream habitats. This paper presents a proposal of a portable fishway to be set on the waterside of a trapezoidal weir and discusses the effect of the proposed fishway on the migration of diadromous aquatic animals in the trapezoidal weir. Field experiments concerning the proposed fishway were carried out at a trapezoidal weir having a slope of 26.5° (Vertical 1: Horizontal 2) and 2.0 m drop height. The field experiments revealed that the juvenile ayu fish (Plecoglossus altivelis) having a body length of 4.4–10 cm could migrate to their upstream habitats through the proposed portable fishway even if the slope of the fishway is 19°. About 120 000 juvenile ayu could migrate upstream via the fishway during 9 d. The migration route of juvenile ayu can be explained on the basis of the flow characteristics in the fishway. Measurements of the flow velocity and the ai...

Detention Basin Retrofit: Optimization of Water Quality Improvement and Flood Control

Abstract: Retrofitting existing stormwater facilities is of critical importance to restoring impaired watersheds. Many existing storm water detention basins were designed solely for stormwater runoff peak discharge magnitude abatement or were under-designed for current water quality control standards. These basins can be retrofitted to trap additional amounts of non-point source pollutants. This study analyzed a detention basin in Morris Township, NJ as an example to demonstrate the tradeoff between water quality benefits and increases in flooding problems resulting from retrofit. As part of the first retrofit, an outlet structure with a small-diameter circular orifice at the bottom and a rectangular weir on the top was placed in front of the existing large diameter outlet pipe. Diameter of the orifice and height of the weir were varied during hydraulic routing. Quantitative relationships were obtained between the increase in stormwater detention time (pollutant removal efficiency) for a defined, small, infrequent water quality storm and the maximum increase in peak outflow rate (flooding impact) for a full range of storms. It was found that beyond a specific weir height, the detention time no longer increased whereas the maximum peak outflow rate increased greatly. The longest detention time that could be achieved was also calculated for different orifice diameters. In addition, effect of different definitions of the water quality storm on the achievable detention time was quantified.

Non-powered automatic erecting/falling gate using change in water level of weir or the like

Abstract: PROBLEM TO BE SOLVED: To provide an erecting/falling gate capable of moving according to water level without attendance of an operator, dispenses with a drive unit such as a hydraulic cylinder, hydraulic equipment such as an oil pressure generating device, electric control equipment such as a control panel, and an operating chamber for protecting the electric control equipment etc., and saving a large amount of costs required for setting and maintenance of the equipment. SOLUTION: A door body 2 has a vent hole 2b and an intake port 2c at an upper portion thereof, and a drain port 2d which is smaller in a cross section than the intake port 2c, at a lower end thereof, and is formed into a hollow sealed structure 2e. Then the lower portion of the door body 2 is rotatably fixed to a bearing portion 3 in a bottom surface of the water-intake weir 1 which has an engaging portion 5 for engaging with the erected door body 2. Thus the door body 2 is automatically erected without power until water in the water-intake weir 1 reaches a predetermined water level, to thereby stop the inflow of water from the water-intake weir 1 to a drainage station 4. On the other hand when water in the weir 1 exceeds the predetermined water level, the erected door body 2 is made to automatically fall and submerged in the water without power, to thereby water is made to flow from the water-intake weir 1 to the station 4. COPYRIGHT: (C)2004,JPO&NCIPI

Margaret River Fishway

Abstract: In order to enhance the migrations of fish species in the Margaret River, the Margaret River Regional Environment Centre, in conjunction with the Department of Environment, constructed a rock ramp fishway at the Margaret River Weir (Apex Weir) between March and April 2003. Morgan and Beatty (2003) surveyed the fish fauna of the river during March 2003, capturing 9206 fish from five native species, one feral species and the pouched lamprey (Geotria australis) (see Plate 1). All of the native fishes of the river are endemic to south-western Australia while the feral species is the mosquitofish (Gambusia holbrooki). The only other records of fish from the river are those recorded by Morgan et al. (1998) and there are also a few records in the Western Australian Museum. Large numbers of native fishes were known to be impeded by the town weir on their upstream migration during winter and spring. These native fishes included the western minnow (Galaxias occidentalis), western pygmy perch (Edelia vittata) and nightfish (Bostockia porosa). Furthermore, adult lampreys were often observed negotiating the weirs on Margaret River with the occasional dead animal also observed. The reservoir above the Margaret River Weir had the highest abundance of the feral mosquitofish with this section of the river also containing western minnows, nightfish and western pygmy perch, and beds for larval lampreys (ammocoetes) (Morgan and Beatty 2003). It was thus deemed appropriate that the construction of a fishway on the Margaret River would be beneficial to fish and lamprey migrations in the Margaret River.

Weir type flow meter

Abstract: PROBLEM TO BE SOLVED: To enable a precise detection of a flow rate by improving a measuring resolution and eliminating a measuring error. SOLUTION: A weir type flow meter 1 comprises a weir plate 5 damming at least a part of a gate waterway 3, and a water level detector 7 detecting the water level in the upper stream of this weir plate 5. In the weir type flow meter 1, measuring the flow rate of the gate waterway 3 based on the detected water level, the water level detector 7 is installed at a position of a flow rate of zero on the weir plate 5 and only the head of overflow water of the weir plate 5 is detected. COPYRIGHT: (C)2004,JPO&NCIPI

Waterway forming body

Abstract: PROBLEM TO BE SOLVED: To provide a waterway forming body which allows water to smoothly flow therein by relatively raising the water level even when water quantity is small. SOLUTION: The waterway forming body has a single or a plurality of linear protrusions formed on an inner bottom surface thereof in a longitudinal direction, and a guide weir arranged on one end thereof. The guide weir blocks a specific one of waterways defined by the linear projections and guides water to the other waterway. COPYRIGHT: (C)2005,JPO&NCIPI

Gewässergütemodellierung einer Stauhaltung an der unteren Saale

Abstract: In order to investigate the effect locks and weirs have on the substance transport of the Saale river, a water quality modelling exercise with a high spatial and temporal resolution was carried out for the lock-and-weir system at Calbe, approximately 20 km upstream from the mouth of the Saale which flows into the Elbe river. The simulation program WASPS, which was developed by the U.S. Environmental Protection Agency, and a data set from both a seasonal and a diurnal sampling program was used for the modelling. In comparison to a large-scale model of the Saale differences arose in the importance substance concentrations in the sediment and oxygen input via the weir play in the overall substance regime of the lock-and-weir system. In addition, the weir also has a strong influence on the deposition/erosion behaviour of particulate matter. Increased sedimentation directly upstream from the weir reduces heavy metal concentrations in the overlying water column whereas immediately downstream from the weir, higher resuspension rates increase the heavy metal concentrations in the water.

Large volume reactor with a plurality of process chambers

Abstract: A large volume reactor (10) treats a liquid or semi-liquid material and has a housing (12) around a chamber (14) with an inlet (11) and an outlet (13). The chamber has a rotor shaft (22) advancing ingredients towards the outlet. The chamber (14) is sub-divided into two (18', 18) by a weir partition (16). The weir (24) has passages (26) between an inlet (40) and an outlet (42). The weir (24) incorporates an active system driving liquid or semi-liquid ingredients through the passages (26), e.g. an interlocking twin-helical feed pump (28). The pump speed is variable. The weir passage (26) is in a plane at right angles to the rotor shaft. The pump axles rotate and rest in seals within the weir walls. Further claimed is a large volume reactor whose inner volume is sub-divided by multiple weir partitions.

Improved water decanter

Abstract: The utility model relates to an improvement of a decanter which is used on water treatment, in particular to an improvement of decantation weir of a large-scale decanter of long type. The utility model is characterized in that an influent weir of a decantation tank is fitted together by many horizontal adjustable short plates. The integral influent weir is divided into many adjustable weirs and fitted together by these adjustable weirs in the utility model. Therefore the utility model can ensure high level linear degree of the decantation weir thereby achieving not only homogeneous decantation, accordant burthen, but also easy processing and producing, conquering the defect of existing technology of which the integral long folded plate weir is hard to machining. The high level linear degree of the decantation weir can avoid twisting vibration of the decantation tank effectively which resulted in asymmetrical burthen thereby making on a long working life. Simultaneously, joins of many weirs can make on horizontal adjustment of the simple long decantation tank and conquer the defect of which an integral long weir metamorphoses easily.

Study on discharge capacity and hydroelastic model of labyrinth weir

Abstract: Labyrinth weir has special hydraulics characteristics among the uncontrolled spillway and is a popular type of weirIts discharge capacity is greater than that of others but has a lot of influence factors Based on the theoretical analysis and the model experiment,the formula of discharge coefficient to determine the discharge capacity is carried out in this paper By means of the experiment of hydroelastic model,the characteristics of flow induced vibration and anti seismic capacity is studied The result is satisfactory and it can be provided for the reference of design

A supporting type labyrinth weir

Abstract: The utility model discloses a self-retaining labyrinth weir, comprising a soleplate and labyrinth weir walls. The utility model is characterized in that the upper parts of the outer sides of opposite weir walls are provided with evenly distributed horizontal support beams; the outermost support beams between two opposite weir walls can adopt the following forms: a, horizontal support beam, b, slanting support beam; the upper ends are connected with the weir walls and the lower ends are connected with the soleplate. Since the upper parts of the outer sides of the weir walls are provided with a plurality of horizontal support beams with even intervals, the cantilever of the weir walls is free from pressure. Therefore the utility model has the advantages that the size of the weir walls and the soleplate is small; the amount of needed reinforcement metal is small; the engineering cost is remarkably reduced.

Monitoring the Lion’s Weir Fishway Hotham River, Western Australia

Abstract: This report has two major components: PART I Fish fauna of the Hotham River (including the impact of the Lion’s Weir on fish migration) Part I of the study was conducted prior to the construction of the Lion’s Weir Fishway and reports on the fish fauna of 22 sites in the Hotham and Williams River catchments and the impact of the Lion’s Weir on fish migrations. Salinisation of the catchment and species salinity tolerances were found to be the main determinant of fish distributions. PART II Fish utilisation of the Lion’s Weir Fishway Part II provides data on fish utilisation of the Lion’s Weir Fishway between late July and November 2003.