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Ponds, ponds, ponds...

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Title: Ponds, ponds, ponds...


1
Ponds, ponds, ponds...
  • Lecture 5
  • Dr. Craig S. Kasper
  • FAS 1012C Introduction to Aquaculture

2
Acknowledgement
  • Appreciation and sincere thanks are given to Dr.
    Joe Fox (TAMUCC) who kindly donated material for
    this presentation!!
  • Please visit his website!
  • (http//www.sci.tamucc.edu/pals/maric/Index/WEBPAG
    E/mari1.htm)

3
Introduction
  • Ponds were used as one of the first forms of
    aquaculture.
  • Dates back to ancient China.
  • Already had the water...just add fish, feed, and
    presto!
  • Pond production has come along way since then!

4
POND DESIGN CRITERIA (Ideal)
  • Screened inflow gates at shallow end of pond
  • Screened harvest gates at deep end
  • Slope to harvest basin (0.5-1.0)
  • Water depth 1.25 ? 2.00 M
  • Feeding tray piers
  • Rounded or square corners, steps or ramps for
    entry
  • Primary dikes (levees) wide enough to accommodate
    vehicles

5
GENERAL DESIGN, INTENSIVE POND
6
Pond LeveeworkCONSTRUCTION CRITERIA
  • Levees are typically constructed by D6-
    (Catepillar) sized bulldozers
  • Construction is first undertaken on ponds nearest
    the sedimentation basins and pump station
  • Bulldozers push earth up to create general form
    of the levee walls
  • Follow stakes set along the length of the pond
  • Smaller dozers used to put on finishing touches

7
Pond LeveeworkDESIGN CRITERIA
  • Heights determined by pond bottom elevation,
    tidal amplitude
  • Perimeter levee often required for protection in
    flood areas
  • Levees trapezoidal with slopes 12 for high clay,
    13-4 low clay
  • Levee crown width varies with use
  • Width of crown 5 m (driving), 3m (walking)
  • Crown is sloped to reduce puddles on levee top
  • Once formed, levees are sprigged with grass to
    reduce erosion

8
Pond LeveeworkCONSTRUCTION CRITERIA
  • Erosion is the main problem in maintaining levee
    slopes
  • Source both rainfall and wave action
  • Solution plants and vegetation (local grasses
    or Salicornia sp.) as soon as possible
  • Pond sides receiving wind could be reinforced
    with rocks (contracted service)
  • Tops of levees definitely need layer of rocks,
    especially if high clay content

9
Typical Cross-section of Pond Levee
WIDTH4 TO 5 M
CANALSIDE
PONDSIDE
2.0M
2.0M
1.5M
4.0
3.0
CUT-OFFTRENCH
10
Preventing Leaks
  • Minimize amount of loss due to seepage- Proper
    compaction- Core trenching- Vertical plastic
    membranes- Vegetative coverage
  • Remove burrowing animals (turtles, muskrat)
  • (.243 Winchester works great!)
  • Optimal clay content
  • Construction during dry season

11
Pond BottomCONSTRUCTION CRITERIA
  • If detailed pond bottom slopes are required,
    usually accomplished by scrapers
  • Small 4-6 m3 earthmovers towed by 4X4 tractors,
    laser-guided
  • Bottom slope from upper end to lower end of pond
    usually 1m250-500m or 0.4-0.2 for large ponds
  • In simple ponds, follows natural slope to estuary
  • Must insure at least 20 cm height of harvest gate
    above high tide elevation (varies considerably by
    site)

12
POND BOTTOM DESIGNS
crown
canal
canal
canal
canal
plateau
plateau
13
POND BOTTOM ELEVATION
  • Primary design criterion
  • Based upon tidal amplitude (or drainage)
  • Above the freshwater table
  • Above mean high tide
  • Determines canal/levee height
  • Pond should be drainable at all times

14
Pond Bottom vs. Tide
WHERE SHOULD YOU BE????
15
WATER CONTROL STRUCTURESINFLOW GATES
  • Used for control of pond water exchange
  • Concrete structures with screen/bag filters on
    both
  • sides of Levee
  • Dual primary screens for pre-filtration (1/4" to
  • 1/2)
  • Secondary filtration screen bag eliminates
    potential
  • predators (250-500 µM)
  • Flashboards for controlling flow rate of water
  • entering pond
  • Multiple gates in larger ponds

16
LeveeCROWN
LeveeSLOPE
LeveeSLOPE
CONCRETEAPRON
CORRUGATEDPLASTICTUBES
WINGWALL
FLASHBOARDS
BAGFILTER
PRIMARYFILTER
PLAN VIEW OF TYPICAL INFLOW GATE
17
CROSS SECTION OF TYPICAL INFLOW GATE
CANALSIDE
ATTACHMENTSLOT
TOP OF Levee
PONDSIDE
CULVERTPIPE
BAGFILTER
PRIMARYFILTER
FLASHBOARDS
FILTER SLOT
18
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20
WATER CONTROL STRUCTURESHARVEST GATE
  • Concrete w/harvest basin in pond
  • Number/size of gates depends on speed
  • of harvest required
  • Screen to retain shrimp, mesh according to size
  • Use of flashboards
  • Canal side often modified
  • for harvest pump

21
LeveeSLOPE
LeveeCROWN
LeveeSLOPE
DRAINAGECANAL
HARVESTBASIN
PUMP BOX
CULVERT TUBES
NET SLOT
FILTERSCREEN
FLASHBOARD
WINGWALL
PLAN VIEW OF HARVEST GATE
22
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23
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24
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25
Harvest Gate inflow
26
Harvest Gate outflow
27
Harvest Gates outflow
28
Harvest Gates multiple
29
Gate Construction
30
POND AERATION/OXYGENATION
  • level determined by oxygen demand
  • pumping vs. artificial aeration
  • used for oxygenation and solids mobilization
  • efficiency of devices varies
  • paddlewheels 2.13 kg O2/kwh
  • propeller/aspirator 1.58
  • diffusors 0.97

31
Typical Aerators
paddlewheel
air injector
32
Multiple Aeration Units
33
Estimating Oxygen Requirement
  • During paddlewheel aeration and high density
    culture O2 requirement usually estimated on the
    basis of feed application to pond
  • 1 kg of feed 0.2 kg O2 consumed via respiration
  • 300 kg feed 60 kg O2 consumed/day
  • Caveat Some O2 consumed by shrimp/fish, but
    more by primary productivity

34
Estimating Paddlewheel Requirements
Biomass density (kg/ha) Hp (flow-through) Hp (limited water exchange)
lt 1,000 None None
1,000 2,000 2-4 4-8
2,000 4,000 4-8 8-16
4,000 8,000 8-10 16-20
Above 8,000 Above 10 Above 20
35
Additional Paddlewheel Guidelines
  • Use high quality switch boxes and adequate guage
    wire
  • Orient paddlewheels to reduce dead spots in
    ponds (locate in corners) dont change
    orientation during a run
  • More paddlewheels (e.g., 1.0 hp units)
  • fewer dead spots but more (units parts)
  • Stainless steel less corrosion!
  • Pay attention to electrical demand and quality of
    electricity (less motor repair)

36
ELECTRICAL SUPPLY
  • More tecnology more demand!
  • Semi-intensive ponds need electricity for ice
    production, living accomodations, perimeter
    lighting, laboratory, fry acclimation facility
  • Usually provided by diesel generators (more
    dependable and, therefore, cheaper in the long
    run)
  • Intensive and super-intensive operations have
    large energy demand (aeration is about 90 of
    demand)

37
Electrical Distribution
  • Distribution via high tension line with 20-50 kVA
    step-down transformers situated throughout the
    farm
  • Demand could be as high as 50 kVA per ha
  • 300 ha intensive farm could have 3,000 one hp
    paddlewheels 2.5 megawatt demand
  • Electrical distribution system could cost well
    over 1 million

38
ARTIFICIAL SUBSTRATES(POND LINERS)
  • Used in areas where soil quality is poor
    (percolation/toxicity)
  • Also used to reduce effluent solids via erosion
    of pond bottom and drainage canal
  • Cost now 0.25/m2
  • Long-term viability and uv resistance
  • Use at least 30 mil thickness
  • Dont install yourself!!
  • (unless very good at it!)

39
Soil-Cement Liners
  • Made from 16-8 mixture of cement and sand
  • Pond raked down to 3
  • Cement added to achieve ratio
  • Watered and smoothed via 3,000 lb roller
    compactor
  • Rate 1ha/wk

40
Stocking Densities
  • Species dependent
  • -catfish (3500-5000 fish/acre w/aeration)
  • -tilapia... similar
  • -prawn-start with 16,000/acre if substraight
    present
  • -flounder-not density, but bottom coverage,
    usually tolerate 200 bottom coverage if adequate
    water flow.
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