overview of topics swimming ability of juvenile salmonids behavior of juvenile salmonids guiding...
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POSITIVE BARRIER SCREEN AND BYPASS SYSTEM DESIGN
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Overview of Topics
Swimming Ability of Juvenile Salmonids Behavior of Juvenile Salmonids Guiding Juvenile Salmonids Design Development Selecting the Screen Structure Site
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Overview of Topics (continued) Facility Design
CriteriaVelocityScreen Face Materials
Types of Positive Barrier Screens Debris and Sediment Management Approach Velocity Balancing
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Swimming Ability of Juvenile Fish
See references/suggested reading in course notebook.
University of Washington Fisheries Research Institute study (Smith and Carpenter, 1987) was used to develop fish screen approach velocity criterion.
USFWS Bull Trout studies.
Design Fish – Smallest Fry, Coldest Water
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Factors Affecting Swimming Ability Approach velocity, sweeping velocity,
and canal velocity Water Temperature Fish Size Swimming Time Duration Dissolved Oxygen Level
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Swimming Speeds Classification
CruisingSpeed
SustainedSpeed
DartingSpeed
Used for: MigrationAvoidObstacles
EscapePredators
Duration of: Hours Minutes Seconds
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Juvenile Fish Swimming Speeds
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Effect of Temperature on Cruising Velocity
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Effect of Temperature on Critical Velocity
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Effect of Fish Size on Critical Velocity
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Potential Behavioral Factors Effecting Migrating Juvenile Salmonids
Physiology and migration triggers Screen and bypass hydraulic design issues Dams and water diversions – presence, size Reservoir passage – velocity, predators Guidance in dam forebays Available routes of passage
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Reluctance to enter small bypasses Preference for either day or night
migration past screen structures Migration corridors in lakes (mostly
follow shoreline, depth ?) Lateral line function Dissolved Oxygen Level
Potential Behavioral factors (continued)
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Physiology – Migration Effects
Body silvering increases Salinity tolerance increases Growth rate increases Weight per unit length decreases Body total lipid content increases Blood glucose increases Gill microsome, Na, K, ATPase enzyme activity
increases
Smolt (migrating) characteristics compared with parr (non-migrating):
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Fish Size - Migration Timing
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Fish Size - Migration Timing
10 20 2010 2010 2010
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Ave
rage
fork
leng
th o
f mig
rant
s (m
m)
Num
bers
of m
igra
ting
fry
and
sm
olts
(th
ousa
nds)
30
10
0
20
50
40
60
0
20
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4
0
March April May June
A
BTemporal Pattern of Fry andSub-Yearling Smolts in TwoRivers on Vancouver Island
A - Cowichan River - 1967B - Nanaimo River - 1980
Source: Groot and Margolis 1991
CHINOOK RUN TIMING
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River Flow – Migration Effects
Diurnal migration effect
0 12
34
5
6
78
910
11121314
1516
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1920
2122
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+
Arrival of juvenile sockeye salmon at Rocky Reachsampler
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Positive Barrier Screens (PBS)Fish screen or rack to prevent fish entry
into diversionPreferred screen design - guide fish to
bypass without contacting screen
Behavioral DevicesNot acceptable as stand alone deviceCould enhance performance of PBS
Methods of Guiding Juvenile Salmonids
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Vertical Fixed-Plate Screens Traveling Screens
Panel screensBelt Screens
Pump Intake Screens/End of Pipe ScreensFixed Cylindrical Screen Cone screens
Eicher Screens (penstocks) Modular Inclined Screens Non-vertical Fixed Screens Rotating Drum Screens (canal screens)
Examples of Positive Barrier Screens
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Examples of Behavioral Devices
Sound Light Electric Fields Hydraulic Action
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Design Objectives Guide Fish Past Screens:
Without contacting screen - impingementWithout entrainment through seals, mesh,
other gapsWithout delay – good guidance to bypassWithout injury or mortalityMinimizing stress to fishMinimizing predation potential
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Selecting the Screen Structure Site Minimize delay O&M considerations On-River site Off-River site Hydraulics, Hydrology Head needed for bypass operation Bank characteristics Data Collection (see Notebook)
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Off-Channel Diversion
Off-Channel Screen
Site Selection – Off Channel
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Turning Vanes to Correct Channel Approach Flow Conditions
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On-Channel Diversion
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Other Site Considerations Diversion Canal as Fish Habitat Diversion Operations – Pitfalls Starting and Stopping of Diversions
Considering Screen Project Priority
Potential number of fish entrained Existing level of protection Funding ESA Land ownership Proximity to other projects Frequency of diversion Type of diversion
Hypothetical Screen Prioritization Problem
Break
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Screen Design
Design FeaturesFlow-Screen AngleUniform Approach VelocityChannel ConfigurationTrashracksSealsCleaning System
Effective Flow Area
Effective Flow Area: Defined as the total submerged screen area, excluding area blocked by major structural members, but including the screen face material. For rotating drum screens, effective screen area consists only of the submerged area projected onto a vertical plane (i.e. a rectangular area).
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Screen Velocity Criteria (NMFS NWR)Approach Velocity (Va)
• Definition: Va is the canal velocity component perpendicular to the screen face.
• Va must be less than or equal to 0.4 ft/s, at all diverted flow levels and all water surface elevations.
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Screen Velocity Criteria (NMFS NWR)
Approach Velocity (Va)
• The basis for the approach velocity criterion is that salmonid fry swimming for less than one minute, can avoid impingement if screen approach velocity is less than 0.4 feet per second.
• This was developed by testing salmonid fry for sustained swimming stamina in temperatures as low as 4 degrees Celsius.
• Stamina swim tests for salmonid fry conducted at U. of Washington in 1987 by L.S. Smith and L.T. Carpenter – repeated by others, with similar results.
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Screen Velocity Criteria (NMFS NWR)
Achieving Uniform Approach Velocity (Va)
• The screen design must provide for nearly uniform flow distribution over the screen surface, thereby minimizing Va over the entire screen face.
• Uniform flow distribution avoids localized areas of high Va, which have the potential to impinge fish.
• Providing adjustable porosity control on the downstream side of screens, and/or flow training walls may be required. Large facilities may require hydraulic modeling to identify and correct areas of concern. More on this later.
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Approach Velocity – Simplest Case
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Screen Velocity Criteria (NMFS NWR)
Sweeping Velocity (Vs)
• Definition: Vs is the canal velocity component parallel to the screen face.
• Vs must be at least twice the approach velocity, must not decelerate or rapidly accelerate.
• Vs acts to move fish (and debris) toward bypass. Lab studies and field experience have shown that smooth sweeping velocity reduces migration delay.
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Screen Velocity Criteria (NMFS NWR)
Sweeping Velocity (Vs)
•Vs must be sufficient to sweep a motionless fish to a bypass entrance in less than 60 seconds (exposure time criterion).
• Screens longer than 6 feet must be angled and must have Vs greater than Va (tests at Battele Labs). This angle may be dictated by site-specific geometry, hydraulic, and sediment conditions.
• Optimally, Vs should be around 3 ft/s.
Velocity Vectors – Va and VsV
cana
l = V
Vapproach = Va
Scr
een
Face
Vsw
eep
= V
s
өө
Va = V * sin ө
Vs = V * cos ө
Where ө is the angle between the screen face and the canal wall
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Likely (but not always) Orientation of Juvenile Fish in Front of Screens
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Screen Face Materials - Overview
Continuous Slots - Criterion
To protect the smallest salmonid fry:
Maximum Slot Size = 1.75 mm
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Continuous Slots – Vee Wire
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Continuous Slots - Profile Bar
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“Continuous Slots” – Intralox (plastic)
Woven Wire Fabric - Criteria
To protect the smallest salmonid fry:
Max. Mesh Opening = 3/32 inch (2.38 mm)
Minimum Porosity = 27% Open Area
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Woven Wire (old galvanized – not used anymore)
Woven Mesh on Rotating Drum Screens
Perforated Plate - Criteria
To protect the smallest salmonid fry:
Maximum Opening = 3/32 inch (2.38 mm)
Minimum Porosity = 27% Open Area
Perforated Plate on Rotating Drum Screens
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Perforated Plate
Seals
Screens need to be fitted tightly to structural frames and other civil works.
Where moving screens attach to civil works, seals are mandatory and should be checked at least annual for tightness of fit and wear.
The entire face of the screen must not include gaps greater than the maximum slotted screen opening (1.75 mm).
Bottom Seals
Side Seals