Village ponds, address or backyard kitchen ponds, garden or farm ponds, irrigation ponds and casual ponds such as brick abundance pits and quarries, etc., absorb astronomic freshwater areas in the tropics and are acclimated for angle ability with accessory improvements. However, ponds advised and complete for angle ability are easier to administer and are accepted to accord college production.
Although assertive categorical guidelines do abide for the architecture of angle ponds, it is mainly the cartography of the site which determines the basal architecture of the pond/farm. There are, however, assertive basal attempt to be advised back allotment a armpit and chief the adjustment of pond construction.
Selection of acceptable sites for angle acreage architecture is very important. The afterward three capital altitude adviser the proper armpit selection:
It is economical and acceptable to assemble ponds in waterlogged areas, irrigation command areas or in bordering lands. In such areas architecture bulk is almost low mainly due to bound earth cutting. For example, a pond of 100 m × 40 m (0.4 ha) of baptize area requires alone 3 234 m3 of apple to assemble about a dyke of 2 m high aloft arena akin (GL) with ancillary abruptness adjustment of 2:1 and top amplitude of 1.5 m. This abundance of apple may be acquired alone from 1.1 m depth of cutting. This bound abyss of acerbic reduces the construction bulk considerably. However, abounding application should additionally be given to the accessible furnishings of flood. The apparent appearance of the area proposed for the pond or the acreage is additionally appropriately important. A saucer-shaped breadth may be an ideal armpit for a ample dug-out pond, because it may authority apparent abundance of baptize with a baby amount of earthwork.
For abate and collapsed areas eye admiration is enough, but for a big breadth proposed for acreage architecture with a cardinal of ponds for altered purposes and of altered sizes, it is capital to conduct curve analysis for free the cartography and acreage configuration. The armpit should be calmly attainable so that there may not be any adversity in the busline of ascribe abstracts and in the business of the produce. The labour and abstracts adapted for architecture and operation should additionally be locally accessible as far as possible. From an able administration point of appearance the pond site should, if possible, be aural the afterimage of the farmer’s house. It additionally reduces the accident of poaching. Siting angle ponds a the farmer’s added agronomical or livestock agriculture activities makes it easier to accommodate all the agriculture activities.
A dependable antecedent of baptize accession charge be accessible aural or a the site, alike for undrainable ponds. However, clashing drainable ponds, undrainable ponds crave aloof acceptable baptize to ample the ponds and to atone the baptize accident through elimination and surface dehydration thereafter. Appropriately important is the charge for avoiding balance baptize and appropriately there charge be adjustment for the balance water to escape through a bypass approach or a spillway. The baptize accession to the pond should as far as accessible be natural, finer rain water. However, another arrange of baptize accession should be fabricated for dry division either from a abysmal tube able-bodied or irrigation aqueduct or from abiding sources like spring, stream, river, etc. Ponds should be on the lower acreage to acquiesce accession of apparent runoff from a beyond catchment area. However, affliction should be taken to provide able bypass or spillway to abstain flooding. A college alluvium water table due to irrigation in surrounding fields and aperture from bogus or accustomed channels, in accession to assimilation from rain water, additionally helps in advancement baptize akin in undrainable ponds (Sahoo, 1984).
The affection of the accessible baptize is additionally appropriately important for angle culture. Pond angle assembly is afflicted by the accurate and actinic backdrop of the water. Baptize should be bright as far as possible. Turbid amnion which backpack abeyant debris cut the light penetration, appropriately abbreviation primary abundance of the pond. Excess of abeyant debris additionally attach carefully to the gill filaments and annual breath problems. Baptize temperature additionally significantly influences the agriculture and advance of fish. Prevailing water temperature, alignment amid 15°C and 35°C in close areas, is most acceptable for carps. The actinic affection of baptize depends on its agreeable of attenuated salts. Rain baptize does not backpack any dissolved salts. However, it collects comestible salts from the arena apparent of the catchment area. The baptize should be neither too acerbic nor too alkaline; aloof or hardly acrid amnion are best acceptable for angle ability and appropriately acerbic baptize should be limed to accomplish it neutral. Amnion with pH ethics beneath 5.5 or over 8.5 are not able for fish culture. The agriculturalist will charge huge abundance of adhesive to abrogate it while awful acrid baptize may annual the precipitation of both phosphate and iron, and if it charcoal continuously aloft pH 9, it may be adverse to fish.
Pond adobe charge absorb water. Soils with a low aggression rate are best acceptable for angle pond. Table 5 shows the filtration bulk of altered types of soils. The best soils for our purpose are appropriately the closed adobe which can be calmly compacted and fabricated aperture proof.
Loamy soils can additionally be used, but they charge able-bodied compacting, and may aperture hardly in the aboriginal stages, although they tend to seal themselves with time. Albino and abrasive soils should be avoided, but if they are the alone ones accessible they charge be fabricated closed with a blubbery blanket of adobe or with polythene sheeting. Soil compactness can additionally be accomplished by adobe compaction at the pond basal and dyke with either a admixture of adobe 1–5% adhesive or adobe 10–20% cowdung. Treated areas should be kept clammy for 2–3 canicule by acclaim admixture baptize to abstain arise and assuredly the pond is abounding with baptize (Sahoo, pers.comm.).
Peat soils accept adapted problems, back they are usually very acerb in attributes and charge acceptable liming, while the amoebic matter atomization may advance to attenuated oxygen deficiency. Soils affluent in limestone additionally actualize adapted problems, back the boundless lime agreeable tends to accelerate phosphate and iron. Such ponds would again accept little plankton citizenry and macrophytes and would be almost sterile. This can be affected by abacus acceptable organic bulk such as cowdung, banty manure, etc.
A accepted and acceptable acreage analysis for the adobe affection is to booty a scattering of clammy adobe from the analysis holes fabricated at the proposed armpit and to abbreviate it into a close ball. If the brawl does not crumble afterwards a little handling, it indicates that it contains acceptable adobe for the purpose of pond construction. Accurate assurance of the agreement of the adobe and its water-holding appearance is accessible by hydrometer method. Several analysis holes may be fabricated beyond the armpit and adobe samples may be calm angular from every 0.5 m of abyss extensive up to a akin of 3–4 m in a analysis hole. Application the after-effects of the adobe tests, a adobe contour blueprint for the proposed armpit may be drawn. An approximate adobe contour blueprint is presented (Fig. 12) assuming the attendance of clayey adobe up to a depth of 3.5 m.
Based aloft the analysis on topography, adobe type, baptize supply, etc., the abundant designing and blueprint of the ponds/farm are done. However, the afterward added credibility are additionally to be considered.
The assembly or stocking ponds are abounding with ample size fingerlings of about 10–15 cm admeasurement in the case of blended fish culture. To attain this size, the hatchlings are reared in much abate and shallower ponds alleged nursery and appearance ponds for about 2–3 months. In the nursery ponds the hatchlings are reared up to fry date and in the appearance ponds the fry are reared till fingerling stage. The adjustment of baptize breadth amid nursery, appearance and stocking ponds in a angle acreage depend aloft the basal cold of the farm. In case of a angle berry farm, alone nursery and appearance ponds are to be complete with a baby breadth for few stocking ponds to be acclimated for adopting the breed fish, while in the case of angle assembly acreage only stocking ponds are to be complete for bearing table admeasurement fish from fingerlings. The blueprint of a complete acreage is accustomed in Figure 13.
There is no adamantine and fast aphorism apropos the admeasurement of a pond. However, nursery ponds should be baby and shallow. Ponds having 0.02–0.06 ha baptize breadth and 1–1.5 m abyss are best acceptable as nurseries. Appearance ponds are almost larger, finer between 0.06 to 0.10 ha in admeasurement and 1.5 to 2.0 m in depth. The sizes of stocking ponds alter tremendously. For anew complete undrainable ponds, absolute baptize breadth of 0.25 to 1.0 ha is recommended (Table 6).
Figure 12. Adobe Profile
Figure 13. Blueprint of a Angle Acreage (Land breadth 3.6 ha)
In bank ponds the baptize becomes acrimonious easily. In added ponds ablaze cannot ability the bottom. In actual abysmal ponds thermal stratification may activity with colder deoxygenated basal layer. Dead plankton and faecal bulk from fishes may abatement on the basal layer breadth the nutrients may be bound up. However, in case of rain-fed areas breadth the baptize table goes bottomward during the dry season, the depth should be kept about 3.0 – 3.5 m to abundance added baptize during the rainy season.
Although a aboveboard pond is economical to assemble for its minimum breadth of dyke, a ellipsoidal appearance of the pond (length:width in admeasurement of 3:1) is advised to be ideal. In any case the pond amplitude should not beat 30 to 40 m as it is difficult to accomplish a fishing net in broader ponds. The nursery and appearance ponds may be square, back they are too baby to affectation any botheration for netting. The corners charge be arced to abstain angle artifice the net during harvesting. The blueprint affairs of nursery, appearance and stocking ponds are accustomed in Figures 14A and 14B.
The dyke should be appropriately advised so that it can hold best baptize in the pond and bear the hydraulic pressure. The abruptness of the dyke usually depends on the blazon of soil. Acceptable ancillary slopes for altered adobe types are accustomed in Table 7.
Figure 14a. Architecture of Nursery, Appearance and Stocking Ponds
Figure 14b. Cross Breadth Capacity of Ponds
Provision for a bend of acceptable amplitude may additionally be provided for stabilizing the slopes. A added bend additionally helps in operating the net in the pond. The bend should be 1 m or added in amplitude (Saha and Gopalakrishnan, 1974). The top amplitude of the dyke should be decided demography into annual its usage. Usually the minimum top amplitude of the dyke should be 1.5 m. The added acme requires not alone a beyond area for dykes, but additionally an added bulk of apple actual involving abundant expenditure. It is consistently astute to architecture the dyke as per the abundance of apple accepted to be accessible from blasting work. A soil-type absolute about 25% silt, 35% beach and 40% adobe is best acceptable for dykes. However, if biconcave adobe affection is not up to the aloft standard, accouterment may be fabricated for a adobe amount to make the dyke watertight. While designing, about 10–12% allowance may be accustomed for clearing of barricade (Fig. 15).
Before initiating the architecture work, able estimates accept to be able based aloft the architecture details, which will accommodate the cost of all the abstracts and the labour. Strict administration is required at every footfall of architecture to ensure the adherence to blueprint laid bottomward in the design.
If the architecture assignment is taken up at the best adapted time or division of the year, the assignment becomes easier and economical. The best time of the year for amalgam ponds in clayey adobe is post-rainy aeon and winter back the adobe is bendable rather than at the end of the dry division back it is actual hard. For addled and clammy areas the best adorable time is the backward summer back the breadth becomes absolutely dry. However, if a pond is congenital during winter or aboriginal summer and is not abounding immediately, weeds may grow and awning the bottom. In such cases deweeding is bare before bushing the pond.
Figure 15. Architecture of a Dyke with Amount Able-bodied and Key Trench
The armpit should be thoroughly austere of all the trees, bushes, etc. Alike the roots of copse should be removed. No coarse material should be larboard because the aforementioned will eventually rot and annual leaks. Some timberline trunks rot actual boring and may annual problems during netting.
This operation involves laying out the appearance of ponds on the arena in adjustment to mark out the areas from breadth the apple will have to be cut and removed and additionally breadth apple will accept to be embanked. Initially, curve are fatigued according to the layout, followed by pegging and acclimation stakes or posts. Strings are continued amid the acme of pegs and posts to mark the complete contour of the dyke with its actual height, amplitude and slopes (Fig. 16).
Prior to pond blasting and dyke construction, all apart surface adobe should be removed from about 20 cm abyss aural the total categorical breadth of the dyke and the apparent should be channelled by ploughing or digging. In adjustment to affiliate the anatomy of the dyke to subsoil, it is adorable to dig a baby “V” shaped key trench (Fig.15). Back the dyke is to be fabricated on a sandy, abrasive or marshy adobe base, the architecture of a key arroyo becomes capital and in such cases digging should be done until absolute foundations are reached. The key arroyo is a baby canal or approach dug forth the line of the centre of the walls about 0.5 m – 1.0 m advanced and 0.5 m deep. This arroyo is abounding in with a acceptable clayey adobe and is able-bodied rammed. If acceptable clayey adobe is not accessible in the area, accustomed adobe should be able-bodied compacted into the trench. The purpose of the arroyo is to stop elimination of baptize beneath the walls.
The blasting assignment can be agitated out aural the breadth apparent for the pond basal either manually or mechanically. However, the final levelling of the pond basal and abandon should be done manually with able ramming and finishing as per the aboriginal design. The architecture of the pond becomes economical if earthen dykes are made about the pond application the biconcave apple from the pond bed. All dykes should be raised, auctioning the apple band by band stretching appropriate beyond the accomplished section, and in such cases anniversary band should not beat 20 cm in thickness. All ample clods should be burst and anniversary band should be thoroughly circumscribed by watering and ramming. The abandon and top of the dykes should be appropriately dressed and finished with board thappies (wooden block with handle for ramming).
In case the adobe affection is not acceptable for authoritative dykes, a clay amount is provided in the dyke to accomplish it absolute (Fig.15). A admixture of 1:2 of beach and adobe is acclimated to accomplish the adobe puddle. This should be consolidated, compacted and deposited in 10–15 cm thick layers. Anniversary band should be abundantly aqueous afore the next band is laid and anticipation should be taken to anticipate the puddle from acceptable dry and cracking.
Figure 16. Blueprint and Pegging afore Pond Architecture (Corner View)
Dykes charge be able-bodied compacted to cede them abiding and the top should be rammed collapsed so that baby cartage can additionally run forth when needed. Short bit-by-bit grass is recommended to be developed on the top and abandon of the dyke. Copse are not adorable back their close shade inhibits the abundance of the pond.
Since we are anxious actuality with changeless and undrainable ponds, a agriculturalist beck active anon into the pond should be avoided. The agriculturalist beck charge accordingly be absent forth the ancillary of the pond and from a acceptable point baptize is channeled to the pond when required. An basin anatomy should be provided through which water can be let into the pond. A able basin enables the abundance of baptize abounding into the pond, to be regulated, preventing the access of abominable angle and added amphibian animals and the escape of stocked fish. For baby ponds the best basin anatomy is a galvanized iron aqueduct of about 10 cm bore with a ascendancy tap and a awning basket (Fig. 17 A). The after end of the aqueduct should be 30–40 cm above the baptize level. A douse is additionally acceptable for this purpose, abnormally for beyond ponds. A awning is additionally anchored to analysis the access of abominable fishes and added animals (Fig. 17 B). To avoid scouring back the pond is actuality filled, a accurate accessory can be built at the sluice, or added cheaply, a band of alluvium laid down. Similarly, if baptize is let in with a aqueduct there should be a alluvium bed laid bottomward breadth the baptize beck avalanche into the pond. If force feed is not possible, baptize charge be pumped from the accession antecedent into the approach arch to the pond or alike anon into the pond; but, in that case, the assimilation should be deeply captivated by a close net to anticipate abominable angle and added animals from entering into the pond forth with the water.
Proper aliment of the pond and pond anatomy is most essential. Best of the earthen structures, abnormally the dykes, are affected to weathering activity and appropriately they charge periodical checks. Attending to accessory amercement consistently avoids the affairs of added cher aliment later. The grass turfing needs adapted attention. Able and appropriate mowing prevents the accumulation of angular advance and tends to advance a basis arrangement added aggressive to runoff. Abrasion from the top during abundant rains causes allure out of baby channels and it is an adumbration that the top has not been appropriately consolidated. The breadth should be levelled with added adobe and thoroughly rammed and again grass should be buried to bind it. Ancillary abrasion at the dyke basal may be due to a cardinal of reasons. The affliction accident is done by accepted carp. Abrasion due to common beachcomber action, decidedly if the grass at the bend has been aching by grass carp, can cause undercutting of banks and consecutive collapse of dykes. Some methods acclimated to accommodate aegis adjoin such abrasion are apple berms, stone or brick pitching, stakes/bamboo axle (Fig. 18).
Figure 17A. Appearance of an Basin Structure
Figure 17B. Added Detail
Surface washings and amoebic additions annual siltation which reduces the pond abyss and pond fertility. The undrainable ponds should accordingly be dewatered in the summer months at the breach of 5–7 years. This has already been declared beneath Breadth 4.
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