CONSTRUCTION OF FISH PONDINTRODUCTION:Ponds are dug in the ground or formed behind bunds on one, two, three or four sides, which can be made of earth or building materials such as concrete. Any pond can be used to grow fish, but a pond that is dug specially for fish culture usually has a regular shape, a flat bottom with a slight slope along its length. When deciding where to locate a new pond, you should consider the landscape (find a moderate elevation, gentle 2% or less slope, well drained and not prone to flooding), land use (remember - all sources of water contributing to the pond should be free of sediment, pesticides and other forms of pollution), soil texture (15% clay is best for pond construction and water holding), water supply (consider quality, quantity and seasonality), security (from theft) and convenience (maybe close to your house).

TYPES OF POND FOR FISH CULTURE:i. NURSERY POND: The smallest and shallowest of ponds for fish culture is

a nursery pond. This is about 0.02-0.05 ha. The water is about 1 m deep.ii. REARING POND: A rearing pond is larger than a nursery pond. It is 0.08-

0.2 ha. The water is about 1.5-2.0 m deep. Nursery and rearing ponds can be seasonal.

iii. STOCKING POND: A stocking pond is much larger, often 0.2-2.0 ha. It should be 2.0-3.5 m deep. This pond might be perennial or seasonal.

iv. MARKETING P0ND : A marketing pond, which is small but quite deep, is used to keep fish caught from a stocking pond for sale at short notice when the demand and price are high. These ponds can be 0.05-0.10 ha in size with a water level of 3-4 m in summer.

v. BROOD STOCK POND : Brood stock ponds (0.2-0.4 ha) are perennial and have a water depth of 2 m in the summer

vi. QUARTINE POND: Fish brought in from outside are first placed in a small (0.02 ha) but perennial (1.5 m deep) quarantine pond for a time to verify that they are not infected. You can also use this pond to treat diseased fish from other ponds. The one in the picture is concrete lined.

Figure: A nursery pond Figure: A rearing pond

Figure: A stocking pond Figure: A marketing pond

Figure: A quarantine pond Figure: A brood stock pond

Figure: different types of ponds

HOW TO SELECT A SUITABLE SITE TO CONSTRUCT A POND FOR FISH CULTURE:IMPORTANCE OF SITE SELECTION:

The first step or the most important preconstruction activity is to select a correct site as careful site selection is a pre-requisite in pond construction. Improper site selection may lead to:

1) Difficulties in holding water in the pond.2) High seepage3) Dike erosion4) Low productivity of the pond, resulting low yields and economic loss.5) Inability to drain water completely, and6) Difficulties in harvesting

FACTORS SHOULD BE CONSIDERED IN SELECTION OF SUITABLE SITE FOR POND CONSTRUCTION:There are several factors a farmer should consider in selection of a suitable site. The most important are:

A. Space availability and topography of the site,B. Water supply and quality, andC. Soil quality

A. SPACE AVAILABILITY AND TOPOGRAPHY: The site should at least have a space of 200 m2 to construct a pond. It is better to select flat land or lands with a slight gradient. Sites with slight gradients (0.5 to 3 percent is better. Avoid sites with

gradients more than 5 percent) have the advantage of obtaining water into the pond and drain water out from the pond by gravity. Try to avoid areas with large undulations and rocks and with large trees. This type of areas will increase the construction cost and also prevent good sunlight into the pond.

B. WATER SUPPLY AND WATER QUALITY: I. Water source: The site should be adjacent to or in close proximity to a suitable water source in order to fill the pond easily. The source of water should have adequate amount of water with required

quality to supply water into the pond throughout the year or at least throughout grater part of the year.

The water should not be acidic and should be free from pollutants such as waste and pesticides.

Streams, large rivers, small rivers, lakes and reservoirs can be used as water sources.

Stream and river water is generally rich in dissolved oxygen than lakes and reservoirs.

With respect to state of pollution all these water sources can have same pollution problems, but reservoirs and lakes are relatively slow than streams and rivers in recovering from the pollution state.

II. Water quality: The most important water quality parameters in freshwater ponds are

temperature, pH value, dissolved oxygen Temperature influences almost all the physiological activities of

fish/shrimp such as respiration, growth, feeding, molting, disease resistance.

- In general the suitable range for tropical fish is 25 to 300 C. The Dissolved oxygen in water is one of the most important water quality

parameter to maintain a healthy pond environment.- The dissolved oxygen level of 5.0 to 6.0 mg/liter is better for many fish.

pH value will tell you whether water is acidic or otherwise (basic). The pH of pond water is a good indication of health of fish and pond environment.

- For most of fish a pH value between 6-8.5 is better.C. SOIL QUALITY:

Soil quality should be considered in two ways

I. Physical quality, andII. Chemical quality

I. Physical quality: Soil has particles of various sizes, namely, sand, silt and clay. Among

these three types sand is the largest and clay is the finest. The relative amount (percentages) of these three sizes is known as soil texture.

Pond soil should have enough clay to hold water and prevent erosion of pond dike.

100% clay is not suitable for pond construction, since the pond dikes crack when expose to sunlight.

Once the dikes are cracked, they get weak and water may leak out.

II. Chemical quality: Your pond soil should not be acidic Acidic-soils reduce the pond productivity. For example growth of algae,

which is natural food for many fish and essential for a good pond environment, may be greatly reduced.

Acidic-soils make the pond water acidic Acidic-water retards growth of fish and causes stress situation favoring

infections and diseases

LAYING OUT FISH PONDS:PONDS LAY OUT DESIGN:

Pond layout can be done either in a series or parallel.

The advantage of arranging the ponds in a series is it is cost effective when compared to arranging in parallel.

Figure: Ponds arranged in series

However, it has the disadvantage of difficulties in maintaining a healthy pond environment as it has a greater risk of spreading disease and contaminations from one pond to the other. Therefore, it is not a good

option.

Figure: Ponds arranged in parallel

ALIGN POND DIRECTION:

Wind plays a role in fishpond design. Strong wind generates waves and the waves break on the dikes, it will to erode the sides of the dikes.

To minimize this, position the longer pond dimensions (longer pond axis) parallel to the direction of the main prevailing wind direction so that the wave action would be on shorter length of dikes and erosion would be

less.

PROTECTION FROM FLOOD :

If the fish pond site is prone to flooding, construct a diversion canal along the perimeter dike to divert runoff water during heavy rains.

Construct a larger and higher perimeter dike to prevent inflow of water.

DESIGN OF THE POND BOTTOM:

Pond bottom should be flat and sloping towards the outlet or drainage gate with a gentle gradient.

For small ponds keep a gentle slope of the pond bottom of about 0.5% to 1.0% from the water inlet to water outlet or drainage gate to ensure easy and complete drainage of the pond.

If you have problems to excavate the bottom of the pond to hold water up to the required depth, you may construct peripheral and/or central ditches or canals in the pond bottom to provide deep areas for fish.

These canals or ditches should be 0.25 - 0.5 m X 0.25 – 0.5 m.

(Include a sketch with a cross section to show the peripheral and central canals)

CONSTRUCTION OF DIKE:Dikes are the most important part of a fish pond, as they keep the necessary volume of water impounded and form the actual pond; their design and construction is particularly important

CHARACTERISTICS OF POND DIKES:Any pond dike should have three basic qualities.

(a) It should be able to resist the water pressure resulting from the pond water depth.

(b) It should be impervious, the water seepage through the dike being kept to a minimum.

(c) It should be high enough to keep the pond water from ever running over its top,which would rapidly destroy the dike.

Figure: characteristics of dikes

ENSURING IMPERMEABILITY:

Impermeability of the dike can be ensured by:

Using good soil that contains enough clay Building a central clayey core when using pervious soil material; Building a cut-off trench when the foundation is permeable; applying good construction practices Ensuring that the thickness of your dike is appropriate

Figure : Diagram of a pond dike built using sandy soil with a clay core and cut-off trench to ensure impermeability

CHOOSING THE RIGHT HEIGHT :

To calculate the height of the dike to be built, take into account:

The depth of the water you want in the pond; The freeboard which is the upper part of a dike and should never be

under water. It varies from 0.25 cm for very small diversion ponds to 1 m for barrage ponds without a diversion canal; the dike height that will be lost during settlement, taking into account the compression of the subsoil by the dike weight and the settling of fresh soil material. This is the settlement allowance which usually varies from 5 to 20 percent of the construction height of the dike (see Section 6.2 and

PREPARING THE FOUNDATIONS OF THE DIKE:

After clearing the site, removing the surface soil and marking out the position of the dike, the foundations of the dike should be prepared. This may include:

I. treating the surface of the foundations;II. excavating and backfilling the cut-off trench;III. Excavating and backfilling an existing stream channel.

I. Treating the surface of the foundations:

The surface of the dike's foundations needs to be well compacted, so that the dike can be solidly attached without any risk of it sliding away.

II. Building a cut-off trench

If the foundation soil does not contain an adequate layer of impervious material at the surface, you should build a cut-off trench (sometimes called a puddle trench) within the dike's foundations. Its main purpose is to reduce water seepage under the dike. It will also help to anchor the dike solidly to its foundations.

Figure: Detail of a cut-off trench dug through a permeable layer of soil into an impermeable layer

III. Backfilling a stream channel

If a stream channel crosses the foundations of the dam, such as in the case of a barrage pond, you must prepare the channel of the stream where the dam will be built. If the water is flowing when you want to work on the channel, you will first have to divert the stream.

Figure: Preparing the stream channel for a barrage pond

PREPARING FOR THE CONSTRUCTION OF THE DIKES:

When the inner and outer limits of the pond have been staked, clear any remaining vegetation from the area.

Remove the surface soil only from the area of the dike bases, as staked out above, and store it close by .

Treat the surface of the foundations of the dikes . According to local soil quality, build either an anchoring trench or a cut-off

trench. Build the water control structures, as necessary . Place the outlet

entrance at an elevation low enough to ensure complete drainage of the pond along the sloping bottom.

FINISHING THE DIKES:

Now the dikes are built with sides that look like staircases. To reform these dikes with smooth side slopes and to finish their construction, proceed in the following way.

(a) On the top of each dike, set out the planned dike crest width, measuring half of its value on either side of the Centre line and marking the limits with wooden pegs and lines.

(b) Starting from the top of the dike, obliquely cut the end of each soil layer on the wet side of the dikes following a slope that joins the limit of the dike crest to the bottom limit of the layers, until reaching the staked-out limit of the dike base.

(c) Repeat this cutting on the dry side of the dikes.

(d) Transport the soil removed, as necessary.

(e) Remove all stakes and lines.

(f)Bring back some of the surface soil on the top of the dikes and on the dry sides.

Figure :Finishing of dikes

PROTECTING DIKES AGAINST EROSION BY RAIN:

I. Newly built dikes should be protected against erosion by planting or seeding a grass cover on the crest of the dikes, on their dry side and on their wet side down to the normal water level of the pond.

II. To form a grass cover with the minimum of delay, proceed as follows:III.When it rains heavily, use temporary protection, such as hay or other

suitable materials, to avoid severe erosion of the dikes until a grass cover is formed.

IV. Never plant large trees on or near dikes because their roots would weaken the dikes. In some areas, vegetable crops and forage bushes can be grown, but care should be taken to select plants with a good ground cover and with roots that do not weaken the dike by penetrating too deeply or disturbing the soil.

V. Care should be taken to keep the dikes in good condition, and only small animals should be allowed to graze or browse on them.

Figure:Characteristics of good dike

0. CONSTRUCTION OF OUTLET:

Outlet structures are built for two main reasons:

I. To keep the water surface in the pond at its optimum level, which usually coincides with the maximum water level designed for the pond;

II. To allow for the complete draining of the pond and harvesting of the fish whenever necessary.

FUNCTIONS OF OUTLET:

I. The amount of time necessary to drain the pond completely is reasonable;II. The flow of the draining water is as uniform as possible to avoid

disturbing the fish excessively;III. There is no loss of fish, especially during the draining period;IV. Water can be drained from the top, bottom or intermediate levels of the

pond;V. Any reasonable excess of water is carried away;VI. The outlet can be easily cleaned and serviced;VII. The construction cost and maintenance are relatively low.

ELEMENTS OF OUTLET:

A collecting area on the inside of the pond, from which the water drains and into which the stock is collected for harvest.

The water control itself, including any drain plugs, valves, control boards, screens and gates.

A means for getting the water to the outside of the pond such as a pipe or a cut through the wall, and/or an overflow structure. In both cases, a protected area on the outside of the wall must prevent the drain water from scouring the walls or drainage channel.

MATERIALS:

Pond outlets can be built in various ways, using different materials such as bamboo, wood, bricks, cement blocks or concrete. There are four main types, which will be discussed in turn:

I. Simple cuts through the dikeII. Simple pipelines and siphons

III. SluicesIV. Monks

I. Simple Outlets for Small Ponds:

Using a cut in the dike

Very small rural ponds can be harvested by cutting the dike open at one of the deepest points of the pond. It is rebuilt when the pond has to be filled again. In such a case:

The dike next to the cut can be damaged, especially if the water in the pond is relatively deep and the water current too strong.

Repairing the dike creates additional work; Figure: Simple Outlets

The quality of the dike can be impaired and the risk of it breaking away increased.

II. Simple Pipe Outlets:

Using a simple pipe and stopper:For small-size and shallow ponds, a straight pipeline with a small diameter can be used as a water outlet. It is important that the pipes be laid down at the lowest point of the pond before the dike is built. You can select one of the following pipes according to availability and cost:

I. Bamboo pipes;II. Galvanized iron pipes;III. Plastic pipes.

Figure: Simple Pipe Outlets:

III. The Sluice Gate:

A sluice gate consists of a protected opening in the pond dike that can be easily closed with wooden boards to regulate water level and can be

Figure: The Sluice Gate

screened to avoid fish losses. Whenever required, it can discharge excess water continuously. As the sluice gate is an open outlet structure, it does not require a base pipe through the dike. It has the same functions as a monk, but has some advantages: A sluice gate is easier to build.

I. Less water leaks within the dike.II. It frightens the fish less and makes their harvesting easier.III. Its water discharge capacity for a given size is usually greater.IV. However, its major disadvantage is that it is more expensive to build

V. The Monk Outlet:

The monk is one of the oldest and most common pond draining structures. It consists of a vertical tower closed with wooden boards to regulate the water level. The water is discharged through a pipeline buried under the dike. A screen keeps the farmed fish from leaving the pond.

A monk has advantages similar to those of the sluice gate. The pond water level is easily controlled and adjusted. It can function as an overflow. It simplifies the fish harvest. In addition, a monk is more easily protected than a sluice gate, and it is more economical to build if the pond dike is large. However, it has the disadvantage of not being very simple to construct, particularly if it is built with bricks or concrete.

The complete monk outlet consists of:

I. A vertical three-sided tower (called the monk).a pipeline running through the dike, which is sealed to the back of the tower at its base;

II. A foundation for the tower and the pipeline; and

III. Grooves to fix the wooden boards and screens which form the fourth side of the monk.

WARTER TRANSPORT SYSTEM:

Several different kinds of structure may be used to transport water on a fish farm. The most common one is the open canal, which we will consider in detail first. Then we will look at other common structures, including:

I. Simple aqueducts to transport water above ground levelII. Short pipelines to transport water above or under another structure

such as a water canal or an access roadIII. Simple siphons to transport water over an obstacle such as a pond dikeIV. Types of open water canals

TYPES OF WATER CANALS:

Different types of open water canals are used on fish farms to transport water, usually by gravity for four main purposes:

I. Feeder canals: to supply water from the main water intake to the fish ponds. In a large farm with several diversion pond units, there is usually a main feeder canal branching into secondary and even tertiary feeder canals;

II. Drainage canals: to evacuate water from the fish ponds, for example toward an existing valley;

III. Diversion canals: to divert excess water away from barrage ponds;IV. Protection canals: to divert water runoff away from the fish ponds.

I. Water feeder canals:

Water feeder canals, or supply canals, connect the main water intake to the various fish rearing facilities of the fish farm, and, in particular, to the diversion ponds.

Special points about feeder canals :

When planning and designing your feeder canals, you should remember the following:

a. The main feeder canal should bring the water to the farm site by gravity at the highest possible level.

b. On the farm sites, the canals should bring water to each facility by gravity.

c. At each facility, to enable its drainage by gravity at any time.d. If pumping is needed, it is usually simpler to pump into a gravity supply

canal, rather than pump out of each pond. Avoid having to do both.e. The level of the canal bottom should ideally be at least 10 cm higher than

the normal water level in the pond it supplies. If the site slope is very

gentle, however, the canal upper surface can be as little as 5 cm above the normal pond water level.

II. Drainage Canals:

Drainage canals are built to carry the water draining from the fish ponds away from the farm site, usually into a lower natural channel.

The design of a particular drainage canal should be based on the pond or series of ponds it will have to drain:

I. For small ponds, (nursery ponds, for example), the drainage canal may be designed to drain more than one pond simultaneously, within a period of perhaps a couple of hours;

II. For medium-size ponds the drainage canal is usually designed to drain the ponds one by one within a reasonable period of time, from half a day to a full day;

III. The design of the drainage canal also depends on the type of pond outlet and its water carrying capacity

IV. For large fish farms, the total drainage time of all the ponds should not exceed 1 day per hectare (or 5 days for a 5-ha water surface and 25 days for 25 ha); the pond outlet structures should be designed accordingly.

III.Diversion Canals:

A diversion canal should be built to divert excess stream water around a barrage pond if the pond is built where there is a likelihood of floods. Such a canal should therefore be deep and wide enough to evacuate the largest flood waters. The diversion canal starts from a diversion structure

Design and construction methods of diversion canals are similar to those given for earthen feeder canals. The following points are of particular importance:

I. The canal's initial bottom level should be equal or slightly lower than the stream bottom level;

II. The canal dimensions should be at least equal to those of the stream channel when in full flood;

III. The canal should be at least 5 m away from the pond banks;IV. When staking out the canal axis, set all the tops of the stakes at the same

level.

POND-BOTTOM DRAINS:

Pond-bottom drains are ditches that are dug on the bottom of the pond to help the water flow out and to direct the fish toward the pond outlet when harvesting.

We do not always need bottom drains for your pond, for example in small ponds with a sloping bottom. However, it is better to build bottom drains:

I. When the bottom slope is insufficient;II. In large ponds more than 75 m long;III. In barrage ponds with an uneven bottom relief.

FIRST FILLING OF THE POND:

As soon as possible and before the completion of the pond, it is advisable to put it under water:

To check that all structures function properly such as the water intake, the canals, the pond inlet and outlet;

To check that the new dikes are strong and impervious enough; To accelerate the stabilization of these dikes.

For maximum security and efficiency, proceed in the following way.

a. Fill the pond with water very slowly and up to a maximum depth of 0.40 m at the outlet.

b. Close the water supply and keep water in the pond for a few days. During this period, check the dikes carefully. Repair crevices and collapsed sections, compacting well.

c. Drain the water completely and leave the pond dry for a few days. Keep checking the dikes and repair them as necessary.

d. Fill the pond again very slowly and up to a maximum level about 0.40 m higher than the previous time.

e. Close the water supply. Check the dikes and repair them as necessary. After a few days, drain the pond completely.

f. Repeat this process of filling/drying until the water level in the pond reaches the designed maximum level.

g. Check and repair the dikes as necessary.

If there is a limited water supply it will not be possible to follow the above procedure. In such a case, fill the pond very slowly and gradually, closing the water supply at regular intervals and checking on the dikes carefully

CONCLUSION:

Aquaculture engineering can be defined as the subject dealing with the theory &practice of applying engineering practice in aquaculture. Successful aquaculture depends on good pond construction .so this assignment will be help for successful aquaculture. We apply this knowledge on future study & our practical life in future.

REFFERENCES:

http://books.google.com.bd/books?Id=Fn3SwUueZaAC&pg=PA209&lpg=PA209&dq=layout+of+pond+construction&source=bl&ots=lextgv-dwj&sig=rpxrrnako0jy3greqpbtyptvf_o&hl=en&sa=X&ei=munmu_K-izkiugtbtok4ag&ved=0CDQQ6AEwBQ#v=onepage&q=layout%20of%20pond%20construction&f=false

http://aquaticcommons.org/1666/1/Better-Practice3_opt.pdf Ftp://ftp.fao.org/fi/cdrom/FAO_training/FAO_training/general/x6708e/

Index.htm http://www.fao.org/docrep/l8156e/l8156e06.htm http://www.business.qld.gov.au/industry/fisheries/aquaculture/site-

selection-and-production/guidelines-for-aquaculture-pond-constructio http://www.supporttofishery.org/wp-content/uploads/2012/06/

GUIDANCE-ON-POND-CONSTRUCTION-2.pdf https://srac.tamu.edu/index.cfm/getfactsheet/whichfactsheet/60/

Http://www.massmind.org/techref/other/pond/tilapiaponds.htm ftp://ftp.fao.org/fi/cdrom/FAO_training/FAO_training/general/x6708e/Index.htm