Outlet and Inlet

·    Behlke, C.  1991.  Power and energy implications of passage structures for fishAmerican Fisheries Society Symposium.  10:289-298.

Abstract
:  Fluid mechanic equations are used to show effects of virtual mass force, non-Archimedean   buoyant force, and profile drag force on fish in several fish passage   structures. Example problems are worked to show computational procedures for calculating   net propulsive force, net power, and net energy necessary for fish to swim in a lake, up a   steep chute, and through the outlet, barrel, and inlet of a culvert. (Author's abstract)

Keywords:
fluid mechanic equation; fish; fish passage; fish passage structure; culvert; steep chute; outlet; barrel; inlet; net propulsive force; net power; net energy; non-Archimedean buoyant force ; research methodology

 

·    Connor, B.  2000. Unpublished work.  Design discharge for juvenile salmon.

Abstract
: The Alaska Department of Fish and Game uses criteria specifically for Arctic grayling to determine stream   discharges that are then used to design culverts for fish passage. While this application is certainly appropriate   where Arctic grayling exist, blind application of designs developed for grayling results in potentially inappropriate   designs for other species. This can be both costly and inefficient. It is know that juvenile salmon use the boundary   layer along the culvert walls to pass through the culvert. Unfortunately, a lack of understanding exists about the   velocities of the flow near the culvert walls. Culvert inlets represent a major barrier to fish passage. Researchers will   investigate methods to remove this barrier. The objectives of this research are to: ( 1) better understanding how inlet   and culvert velocities affect swimming of specific fish species; (2) develop reasonable criteria to determine design   discharges to more closely match geography and fish species; and (3) culvert installations that are neither over- nor   under-designed.  (Author's abstract)

Keywords
: wildlife; salmon; juvenile salmon; fish; culvert; water; stream; flow; velocity; research project; hydrology; behavior; regional; hydraulics

 

·    Day, R. A.  1997.  Preliminary Observations of Turbulent Flow at Culvert InletsJournal of Hydraulic Engineering.  123(2):116-124.

Abstract
:  This paper presents the results of preliminary observations of turbulence at the inlet of a pipe clulvert using bidirectional electromagnetic current meter (ECM).  Instantaneous longitudinal and vertical  components of velocity have been sampled in the approach section to a pipe culvert.  Thi results correspond to a pipe culvert with a sharp edged inlet, r/D =0.015, with relative headwater depths of H/D = 1.62, 1.26, and 0.96, laid on a 0.3% slope.  The distributions of mean velocities, turbulence intensity, and characteristic eddy scales are shown to vary with proximity to the culvert headwall.  It is deminstrated that there is a significant increase in the magnitudes of the mean velocity components and that the distribution of the turbulence intnesity levels and eddy scales undergo significant changes as the flow approaches the inlet. (Author's Abstract)

Keywords:
turbulence; pipe culvert; culvert; hydraulics

 

·    Flanagan, Sam A.  1996.  Woody debris transport through low order stream channels: Implications for stream crossing failure.  Master of Science thesis.  Humbolt State University.

Abstract
: Stream crossings represent a significant erosional risk within a watershed. Knowledge of the processes of stream crossing failure can help land managers better assess the risks posed by crossings. Woody debris is a common initiator of stream crossing failure. This study observed (1) the size distributions of woody debris fluvially transported through 24 small, culverted catchments in three watersheds of northwest California and (2) the characteristics of wood lodged at culvert inlets. Mean and median lengths of wood lodged across culvert inlets were correlated with culvert diameter. Fluvially transported woody debris was exponentially distributed, with abundant smaller pieces. A 95th percentile wood length was chosen to characterize wood lengths among the sites. Channel bed width, the zone of annual bedload transport, was weakly correlated with 95th percentile wood lengths transported. A narrow range of sampled bed widths may explain the scatter in the data. It is hypothesized that relatively wide channel approaches may promote debris lodgement while narrow, restricting channels may favor debris passage through culverts. Culverts oriented at, or near, a ninety degree angle are susceptable to debris lodgement. Susceptibility to plugging cannot be eliminated. Knowledge of the factors influencing plugging is useful for the design and/or assessment of culvert installations. (A)

Keywords
: stream; stream crossing; erosion; watershed; woody debris; woody debris transport; stream channel; channel; stream crossing failure; land management; California; United States; culvert; culvert inlet; culvert design; culvert installation; stream; regional

 

·    Flanagan, Sam A. and Furniss, Michael J.  1997.  Field indicators of inlet controlled road stream crossing capacity.  San Dimas, California.  USDA, Forest Service, San Dimas Technology and Development Center.

Abstract
: Most road stream crossings in wildland   environments exhibit physical evidence of past   crossing performance that can be readily   observed in the field. These observations,   together with more intensive watershed   inventory and assessments, are useful in   determining where crossings are likely to fail and   where crossing upgrades or road   decommissioning may be needed to reduce   adverse effects to aquatic and riparian   ecosystems.   Typically, culverts will possess a suite of   identifiable field features that indicates their past   performance. These features are useful for   screening sites for possible upgrade or removal.   They are intended to add supporting field   evidence to more rigorous inventories and   assessments. These features have been   observed around inlet-controlled culverts   (usually where pipe gradient is greater than   2 percent). Caution should be used when   applying the parameters to outlet-controlled   culverts.   The indicators discussed here are:   · Channel width versus culvert inlet diameter   · Inlet basin geometry   · Terrace development in the inlet basin   · Crushing and plugging of the inlet.   (Authors' introduction)

Keywords
: channel width; road-stream crossing; wildland environment; culvert;  inlet-controlled culvert; culvert inlet diameter; inlet basin geometry; terrace development; inlet crushing; inlet plugging; aquatic ecosystem; riparian ecosystem; field indicator; crossing capacity

 

·    Grimaldi, Carol.  1995.  Improving culvert entrances to increase flow capacity.  San Francisco.  U.S. Department of Agriculture, Forest Service, Pacific Southwest Region, Engineering.:  1-22 pages.

Abstract
: Of the two conditions which limit the flow capacity of culverts, outlet or inlet control, a majority of culverts found on Forest Service roads flow under inlet control. With inlet treatments, velocities through the culvert can be increased, creating culverts capable of handling larger storm events. Five different inlet treatments are considered; projecting inlet, mitered inlet, headwall and wingwall, beveled ring inlet, and side-tapered inlet. Design criteria including fish passage at high velocities and economics; performance curves for best design choice; and examples are given for each treatment

Keywords
: culvert inlet; flow capacity; culvert fish passage; culvert; fish passage

 

·    Katopodis, C. , Robinson, P. R., and Sutherland, B. G.  1978.  A study of model and prototype culvert baffling for fish passage.  Winnepeg, Manitoba, Canada.  Western Region, Fisheries and Marine Service, Department of Fisheries and the Environment.   Fisheries and Marine Service Technical Report.:  1-78 pages.

Abstract
: Most streams, crossed by roads or highways are culverted. Many such   crossings are impassable to migrating fish because of the culvert length and the high water   velocities in them. A hydraulic model study tested and developed devices to aid fish   passage through culverts. Based on the model study recommendations, Offset baffles and   Spoiler baffles were designed and installed at the Mackenzie Highway crossing of the   Redknife River.   Field testing showed good agreement between model and prototype results. The   effectiveness of both baffle types is inversely proportional to culvert slope. Maximum   recommended slope is 5%. A method of judging baffle adequacy is provided. The Offset   and Spoiler baffles are recommended, primarily for correcting existing culvert installations   and for proposed stream crossings where alternative designs are neither practical nor   economical. Minor problems were presented by ice, debris and sediment.   Unsuccessful attempts by Arctic grayling and longnose sucker to enter the Redknife River   were observed. Their failures were attributed to overwhelming water velocities associated   with culvert outlets. (Author's abstract).

Keywords
: culvert; model culvert baffling; culvert baffling; prototype culvert baffling; fish passage; stream; road; road crossing; highway; stream crossing; impassable crossing; migratory fish; fish; culvert length; high water velocity; water velocity; velocity; hydraulic model; spoiler baffle; culvert passage; offset baffle; Redknife River; Manitoba; Canada; baffle; baffle type; baffle adequacy; culvert installation; ice problem; debris; sediment; Arctic grayling; longnose sucker; overwhelming water velocity; culvert outlet; regional; barrier remediation

 

·    Liu Minnan and Zhu, David Z.  2000.  Study of Tunnel Outlet Head-Loss CoefficientCanadian Journal of Civil Engineering .  27(6):1306-1310.

Abstract
:  In the design of diversion tunnels, culverts, and pressurized conduits, the outlet head-loss coefficient is generally assumed to be 1.0. However, the head loss can be reduced if a transitional expansion is added to the conduit outlet. This paper studies the reduction in the outlet loss coefficient by using the wingwalls at the tunnel outlet. The best wingwall diffusion angle is found to be 8°, which gives an outlet loss coefficient of 0.62-0.81 with a wingwall length of 2D, with D being the height of the tunnel. A wingwall length of 2D is also found to be suitable, as further increase in length only reduces the outlet loss coefficient marginally. An illustrating example shows that by adding wingwalls of 8° and a length of 2D the headwater level is decreased by 9-22% compared to the case without wingwalls for the same discharge. (Author’s Abstract)

Keywords:
outlet; loss coefficient; diversion tunnel; wingwall; diffusion angle; culvert

 

·    Montes, J. S.  1997.  New Approach to Design of Culverts (Discussion)Journal of Irrigation and Drainage Engineering.  123(1): 71-72.

Abstract
:  A discussion of B. Dasika's 1995 article entitled "New Approach to Design of Culverts".

Keywords:
  culvert; inlet; outlet; submerged

 

·   Rajaratnam, N., Katopodis, C., and Sabur, M. A.  1991.  Entrance region of circular pipes flowing partly fullJournal of Hydraulic Research.  29:685-698.

 Abstract
:  This paper presents the results of an experimental study on the characteristics of flow in the entrance region of a circular pipe flowing partly full for slopes of 1, 3 and 5%. An analysis of the water surface and velocity profiles in the centerplane indicates the existence of a near-field of the entrance region. At the end of this region, the depth of flow is essentially constant with the velocity in the outer flow (above the boundary layer) having reached a maximum value but the velocity profile is still evolving (in a limited way), associated with the growth of the boundary layer. In this near-field, the flow may be modelled by potential flow with a thin boundary layer of approximately constant thickness. Correlations have been developed for the main characteristics of this near-field. (A) 2 Refs

Keywords:
culvert hydraulics; culvert inlet; flow velocity; hydraulics; culvert

 

·   Ruff, James F., Abt, Steven R., Mendoza, Cesar, Shaikh, A., and Kloberdanz, A. M.  1982.  Scour at culvert outlets in mixed bed materials.  Sterling, VA.  Federal Highway Administration.

Abstract
: The study of localized scour at culvert outlets has been on- going to control and manage erosion along highway embankments. An investigation of scour at culvert outlets was undertaken to refine and extend the state-of-the-art prediction of the dimensions of scour holes. Over 100 experiments ranging from 20 to 1000 minutes in duration were conducted in cohesive and non- cohesive bed materials. Culverts having 4-inch (10.2 cm), 10-inch (25.4 cm), 14-inch (35.6 cm), and 18-inch (45.7 cm) diameters were tested with discharges from .11 cfs (.003 cms) to 29.13 cfs (.82 cms). Tailwater elevations were maintained at zero, 0.25D and 0.45D +/- 0.05D above the culvert inlet where D is the diameter of the culvert. The results yielded a series of empirical relationships expressing the depth, width, length, and volume of scour as a function of the culvert diameter and discharge. Parameters including the shear number, equivalent depth, pipe shape, soil gradation, and extent of scour were investigated. General observations concerning scour, hole formation, growth and stabilization were reported. (A)

Keywords
: scour; erosion control; prediction; culvert outlet; culvert

 

·   Smith, C. D.  and Oak, A. G.  1995.  Culvert inlet efficiencyCanadian Journal of Civil Engineering.  3:611-616.

Abstract
:  The results of experimental work carried out on culvert inlet efficiency at the University of Saskatchewan are reported in this paper. Efficiency is reported in terms of coefficient of discharge when the culvert operates with inlet control, and in terms of the coefficient of entrance loss when the culvert operates with outlet control. A larger coefficient of discharge or a smaller coefficient of entrance loss represents a higher efficiency. Seven different culvert inlets were tested for both inlet and outlet control, and for the headwater level both above and below the elevation of the crown of the pipe at the inlet. The results are reported in nondimensional charts. (A) Refs

Keywords:
culvert inlet; culvert

 

·   Smith, George L. and Hallmark, Dasel E.  1961.  New developments for erosion control at culvert outlets.

Abstract
: Concentration of flow by highway culverts increases the erosive capabilities of the jet of water exiting from the culvert outlet.  A basic design problem is the need for a kinetic energy dissipator to control excessive erosion resulting from concentrated flow.  By excavating a hole downstream from he culvert outlet and lining it with a graded layer of protective material consisting of coarse sand, gravel and boulder, kinetic energy in the vertical dimension may be controlled.  The development of this pre-shaped, armorplated stilling basin is based on laboratory tests for a limited range of flow conditions, boundary geometry, and sediment characteristics.  Results indicate that a graded gravel is effective as protection against erosion from high-velocity flow and waves.  The gravel needs to be graded so that a larger size material is protected from undermining.  The stability of the channel needs to be protected from the kinetic energy from the impinging jet of water as well as from wave action and standing eddies on the channel banks. 

Keywords
: culvert; highway culvert; highway; erosion; erosion control; culvert outlet; kinetic energy dissipator; flow; channel; armorplated stilling basin; road

 

·   Weismann, Richard N.  1989.  Model study of safety grating for culvert inletJournal of Transportation Engineering.  115:130-138.

Abstract
:  The basic design of the grating, recommended by previous researchers, was tested using a 1:10 scale model. Testing was performed over a wide spectrum of flood flows, including flows that exceed the culvert capacity. The grating has only a minor effect on the head-discharge relationship, causing a slight increase in the headwater required to pass given discharge. However, the grating may act as a debris control structure and vigilant maintenance may be required to prevent clogging of the culvert inlet. Neutrally buoyant objects were introduced to the flow to assess the performance of the grating. Because of the parabolic shape of the grating, and object carried to the culvert tends to be pushed up the grating and out of the flow. (Edited author abstract) 5 Refs

Keywords:
flow capacity; culvert inlet; culvert