Choosing a Source of Ground Truth

case, the intake should be securely wrapped by a firm net to prevent undesirable fish and other animals from entering into the pond along with the water.

Function of some Pond Structures

• Drainage Installations

Drainage is the disposal of pond water as required by the procedures of fish farm management.

Many different draining systems are used, but special mention should be made of the monk and sluice gate. For clearer terms, a monk is usually associated with fresh water fish pond while sluice gate is associated more with brackish water fish pond.

Monk

Monk is known to be the best drainage system and it must be built before the construction of embankment. Monk consists of two main parts namely the shaft and the horizontal pipe. Two or three pair of grooves are incorporated in the shaft, one for the screen, the other two for wood boards. The monk has two important functions. When the pond is being filled, it controls the level of the water and prevents escape of the fish. When it is being emptied it permits progressive draining of the pond.

Sluice Gate

There are two main types of sluice gate notably concrete and wooden sluice gates. Both have the same basic, basic principle of construction, but strong and flexible sluice gate should be fitted to brackish water ponds, despite the fact that the wooden is cheaper to construct. Like the monk sluice gate is located at the lowest point of the pond bed within the dyke base. Two component parts of the sluice gate are the floor and the twp walls (with grooves for sluice gate boards).

Sluice gate is a water control structure associated mostly with brackish water pond. It serves the dual role of letting water in and out of the pond during high and low tides respectively.

Water Inlet

Pond water inlet has been amply described by experts as the point or place where water can be let into the pond system. As an important structure water inlet should functionally assure not only a regular and regulatable supply of water for the system, but prevent both the escape of fish from the pond, and the introduction of unwanted fish into the same pond. All ponds should be installed with a water inlet structure with the exception of ponds fed by springs with a regular flow.

(iii) Topography of the area may enhance or limit pond size.

Factor determining the shape of a Fish pond (i) Anticipated method of harvesting.

(ii) Purpose or function (iii) Topography

(iv) Ratio between embankment and water body Typed based on water supply

There are two major types of ponds based on water supply:

(i) Barrage pond: This type of pond is constructed along the main path of flow of river water or stream. Both up-streams and down streams are barricaded with in-let and out-let respectively

Advantages

It does not cost much to construct. There is usually sufficient amount of water all through the culture period.

Disadvantages

When flood occurs, there is the likelihood that the whole pond system can be washed off.

(ii) Diversion or contour pond

This type of pond is constructed in the by-pass of a stream or river. A water supply channel is built for this purpose with a sluice or inlet gate at the entrance to control the volume of water coming in or going out of the pond and also to check on the influx of extraneous materials.

Advantages

It is not prone to any hazard resulting from excessive flooding as compared to barrage type.

There is better control over the site contrary to barrage.

Diversion pond is divided into two types:

(a) Parallel ponds:

Ponds constructed this way are independent of one another in their source of water supply and discharge. All activities relating to filling and draining of water are limited to each pond respectively.

(b) Series ponds:

These are built such that each pond derives its water supply from the other and also empties into another. This is the worst approach to pond design hence it is not recommended as whatever affects one would definitely affect the other.

Types of Ponds Based on the usage

(i) Holding pond: Used to hold fish temporarily in readiness for either transportation or fattening for induced breeding purpose.

(ii) Spawning pond: Used to hold the set of fish intended for artificial propagation (iii) Segregation pond: Used to hold fishes either of the same sex or same species.

(iv) Nursery pond: used to nurse the fry produced during induced breeding into fingerlings.

(v) Grow-out pond: Used to raise fingerlings to table size fish.

Methods of pond construction

The actual construction work entails some knowledge of surveying. Surveying which can be described as measurement science is carried out in three dimensions- distance, elevation and direction. In specific terms, the three types of survey of relevant to pond construction are:

(i) Coastal survey

This has to do with establishment of some defined boundaries of the proposed land for pond construction with appropriate bench mark.

(ii) Topograhis survey

It is constructed to determine the configuration of the land. This is through measurement of the shape and size of any position or portion of the earth surface and representing same on a reduced scale in map form

4.0 Conclusion

Fish ponds are the structural systems designed for fish culture. Their designs vary according to the site of location. Such sites are selected based on the consideration of a variety of factors which determine suitability. Fish pond sites must be carefully selected to achieve the best production results. A well-selected fish pond site already puts some construction economic in view. It goes without saying, that fish ponds built on properly selected sites have a better chance of returns on investments, especially when management is adequate.

5.0 Summary

Fish ponds are enclosure for fish culture, and there are two types based on the terrain of the site under construction: geophore (land-borne) sites and aquaphore (water-borne) sites. Fish pond site selection depends on the nature of the sites: geophore or aquaphore and vary accordingly. The purpose for which fish pond is being planned will affect the choice of site. This may include fish culture, water-storage, irrigation, hydro-electricity, water storage, flood control, lake resort systems, integrated production (rice-fish, poultry) and vegetable growing. The actual constructive of ponds entails some knowledge of surveying which could be cadastral survey and topographic survey. There are two major types of pond based on water supply (barrage and diversion ponds) and five types based on usage (holding ponds, spawning ponds, segregation ponds, nursery ponds and grow-out pond).

6.0 Tutor-Marked Assignment