ENGINEERING INFORMATION

MATERIAL SELECTION FOR TOOL STEELS

Executive mai Doya 1 MATERIAL SELECTION 6:00 AM

Tool steels are steels that are primarily used to make tools used in manufacturing processes as well as for machining metals, woods and plastics. These  steels  are  fabricated into many types of tools or into the cutting and shaping parts of power-driven machinery for various manufacturing operations. They contain tungsten, molybdenum, and other alloying elements that give them extra strength, hardness, and resistance to wear. They can also be termed as special steels which have been developed to form, cut or otherwise change the shape of a material into a finished or semi-finished product. Although forming a small percentage of total steel production, its nature stands a major factor affecting any finished component.<br /><br />Tool steels are generally ingot-cast wrought products, and must be able to withstand high specific loads as well as be stable at elevated temperatures. Other properties possessed are<br /><br />(i)                Slight change to form during hardening<br /><br />(ii)             Little risk of cracking during hardening<br /><br />(iii)           Good wear resistance, good toughness, very good machinability<br /><br />(iv)           A good resistance to decarbonization during heat treatment<br /><br />Tool steels are fabricated in to many types of tools or into cutting and shaping parts of power-driven machinery for various manufacturing operations. They contain Tungsten, Molybdenum and other alloying elements which give them extra strength, hardness and resistance to wear. Because cutting processes involve high local stresses, fractions and considerable heat generation, cutting tool materials as carbon steels (Steel containing 1 to 1.2% carbon), high speed steels (Iron alloys containing tungsten, chromium, vanadium and carbon) Tungsten carbide and diamonds and by such recently developed materials as ceramic, carbide ceramic and aluminum oxide.<br /><br />In many cutting operations fluids are used to cool and lubricate. Cooling increases tool life and helps to stabilize the size of the finished part. Lubrication reduces friction, thus decreasing the heat generated and the power required for a given cut. Cutting fluids include water based solutions, chemically inactive oils, and synthetic fluids.<br /><br />Based on Standard BS4659:1971, tool steels are grouped into six types; high speed, hot-work, cold-work, shock resisting, special purpose and water hardened tool steels.<br /><br />Classification of tool steels is done based on uses and application, composition or heat treatment process. Putting into consideration the constraints of this discussion, classification based on composition will be looked into. We have the classes of Carbon tool steels, low-alloy tool steel and the High Speed Tool Steel (HSS).<br /><br />1.1     CARBON TOOL STEEL<br /><br />They are perhaps the oldest known tool material. In general, carbon tool steels usually contain 1.2% - 1.5% carbon, which are present in the Martensite phase. This gives it the ability to harden. More than 90% of all steels are carbon steels. They contain varying amounts of carbon but not more than 1.65% Mn, 0.60% Si and 0.60% Cu. Increase in carbon increases wear resistance. When heated to recommended temperature, say 1800 -1950 ⁰F, the steel is free of excess carbides that might decrease forge ability. Other alloying elements are frequently used and supplement the carbon i.e. aiding the hardness. They are Silicon, Manganese, Chromium, Vanadium, Cobalt and Molybdenum.<br /><br />Silicon acts as a deoxidizer, though influencing the properties of steel only slightly unless the amount exceeds 0.5% if carbon content is high, Silicon reacts to form Silicon Carbide, which increases hardness and wear resistance but toughness decreases. Sulphur and phosphorus, of 0.3% have a negligible effect on properties. Manganese leads to a greater penetration of hardness.<br /><br />1.2     LOW ALLOY TOOL STEELS<br /><br />These are tool steels with total percentage of alloying element less than 2.5%. Moderate amounts of Cr, Ni, Mn, Si or Mo is added to increase hardenability, as compared to carbon tool steels i.e. their percentage alloying element is higher than that of carbon tool steels. These principal alloying elements are Si, Ni with low or high carbon. Cr a ferrite stabilizer and relatively strong carbide former which behaves differently form Ni, which is an austenite stabilizer and non carbide former.<br /><br />Due to this fact, both possess different effects on low alloy steel. Ni lowers the critical temperature range while Cr raises it. It implies tat the presence of Ni brings about low hardening temperature, slightly lowers annealing temperature and longer annealing times. The reverse is the case for Cr. also Ni-Steel is less machinable due to strong solid solution hardening effect it exerts has it enters the matrix rather than carbide. The reverse is also the case for Cr-Steel.<br /><br />Low alloy tool steels have a specified composition, containing percentages of vanadium, Molybdenum or other elements as well as large amounts of manganese, silicon and copper than regular carbon steels. The low-alloy tool steels cost less than the regular alloy steels because they contain only small amount of the expensive alloying elements. They have however been specially processed to have much more strength then carbon steels of the same weight.<br /><br />The effects of other alloying elements are summarized below:<br /><br />Si<br /><br />1.     Deoxidizer<br /><br />2.     Hardness penetration and increases strength.<br /><br />Mo<br /><br />1.     Increases tempering resistance<br /><br />2.     Increases hardenability and minimizes temper brittleness.<br /><br />Manganese also acts like Ni i.e. lowering the critical temperature, improves rolling and penetration of hardness. The Ni bases are used for manufacturing tools such as shear bladed, stamping tools, thread rolling dies, chisels, brake dies e.t.c. Drills and broaches, knurls and files, tap dies, rock drills, swaging dies are Cr-based.<br /><br />1.3     HIGH SPEED TOOL STEELS<br /><br />The evolution of high-speed cutting tools commenced with the production of Mushet’s self-hardening tungsten-Manganese steel in 1960. The possibilities of such steels for increased rates of machining were not fully appreciated until 1990, when Taylor and White developed the forerunner of modern high-speed tool steels. In addition to tungsten, chromium was found to be essential and a high hardening temperature to be beneficial. The steel resisted tempering up to 600 ⁰C. This allows the tool to cut at speeds of 80-50m/min with its nose at a dull red temperature. The main constituents of high-speed tool steels are 14 or 18% W, 3 to 5% Cr and 0.6%C. Other elements are frequently added to modern steels which vary considerably in composition and cost. 0.09-0.15% Sulphur is sometimes added to give free machining for unground form tools, e.g. gear hobs. Vanadium improves the cutting qualities of the tools and increases the tendency to air harden. Cobalt, often added to the “Super high-speed steel”, raises the temperature of the solidus and enables a higher hardening temperature to be used, with consequent greater solution of carbon. Secondary hardness is marked in such steels, and this permits the use of deep cuts at fast speeds.<br /><br />The molybdenum steel is susceptible to decarburization. The high vanadium steel is somewhat brittle, but it is excellent for cutting very abrasive materials. Vanadium is also added for grain refinement.<br /><br />High speed tool steels are characterized by being heat treatable to very high hardness (Usually Rockwell C64 or over) and of retaining their hardness and cutting ability at temperature as high as 540⁰C, thus permitting truly high-speed machining. Possess good wear resistance, shock resistance, good non-deforming property.<br /><br />High speed tool steels find application in drills, taps, reamers, milling cutters, broaches, power-saw blades, lathe, shaper and planer tool bits.<br /><br />1.4     HEAT TREATMENT<br /><br />HSS are annealed at 850⁰C for four hours, followed by slow cooling. During heating the steel should be protected against oxidation. The annealed structure consists of carbide globules in a matrix of fine Pearlite.<br /><br />HARDENING: When heated at 900⁰C, Austenite forms, but contains about 1.2% C. Quenching produces martensite, which tempers readily and has no advantage over carbon tool steels. To attain maximum cutting efficiency, sufficient carbon and alloying elements must be dissolved in the austenite and for this reason; HSS is heated between 1150 and 1350⁰C. They are carefully preheated up to 850⁰C and then heated rapidly to the hardening temperature so as to minimize grain growth and deoxidation that occur rapidly at such temperature. Holding at the hardening temperature should be sufficient for dissolving that part of the Carbide which can pass into solution at this temperature. The holding time in a molten salt bath for tools10-15mm in thickness may be taken as 8-9secs/mm cross sectional area. Next the tool may be quenched to 425⁰C, kept there until temperature is uniform throughout the section, and then air cooled to room temperature. This reduces the sever stresses otherwise set up if quenched in oil or cooled in air blast without soaking.<br /><br />Carbon and low-alloy steels may be quenched in water or brine.<br /><br />TEMPERING: Since retained Austenite in the structure of the quenched HSS is softer than Martensite and thus lowers the cutting properties, sub zero treatments at a temperature 70-80⁰C below zero, is often applied after 30-60min of hardening to prevent stabilization of the Austenite. Tempering follows at 560⁰C to relieve internal stresses and transform retained Austenite to Martensite.<br /><br />1.5     MICROSTRUCTURE<br /><br />The final structure of HSS consists of carbide globules in a matrix of fine Pearlite.<br /><br />1.6     MECHANICAL AND ENVIRONMENTAL CONSIDERATIONS<br /><br />Carbon tool steels with high percentage carbon should be selected as the cover for the required wear resistance. Also to be noted is the fact that, increase in carbon increases wear resistance but reduces toughness. Tool steels that lack Cr should be kept away form corrosive atmosphere. In situations where high strength steels are to machined, tool steels with greater resistance to tempering at the temperature required for machining should be selected. HSS stands a better option for this condition as they posses longer life, retain sharp edges at high temperatures, provide good finish, they are also possess high resistance to corrosive environments. It should also be noted that in a situation where by a lubricant will be needed in the course of machining, the tool to be selected must be able to withstand corrosion.

MATERIAL SELECTION FOR TOOL STEELS

Tool steels are steels that are primarily used to make tools used in manufacturing processes as well as for machining metals, woods and plas...

FISH POND RECOMMENDATIONS

Executive mai Doya 0 AGRICULTURAL ENGINEERING 5:53 AM

CONCLUSIONS AND RECOMMENDATIONS<br>5.1    Conclusions<br>    The following conclusions were drawn after the design analysis:<br>    Concrete filled hollow block was found worthy for the design and construction of fish pond with minimum service life of ten years when properly designed.<br>    Considering the cost implication in using total reinforcement and the discouragement herewith the fish farmer, intense compaction was only adopted for the bottom floor to account for the undulating nature of the soil and the slight depression as may be caused over time due to service.<br>    Free flow fish ponds were found to give the best result in terms of yield.<br>    Surface free flow was found to be the best design in terms of drainage ease and maintenance and cost implication considered minimal compared to most other types of concrete pond.<br>    The maximum points of failure/cracks were taking care of especially at the joint edges by interlocking of blocks and mass concreting as part of the wall design.<br>    The losses encountered by the pond were found adequate based on the design.<br><br><br><br>5.2        Recommendations<br>    Where cost is not a problem, it is recommended that total reinforcement be used for optimum service life and should follow all the design codes for water containers outlined by CP110 and BS8110 by Reynold and Steedman, Mosley and Bungay and other related authors.<br>    For swampy areas, it is recommended that foundation/footing as well as the bottom floor be completely reinforced.<br>    For soils with low safe bearing pressure, it is recommended that the depth of foundation and design should follow the concept provided by the Rankine equation, given;<br>Depth of foundation;<br>    h = P/w 〖((1-sin∅)/(1+sin∅))〗^2<br>where     P = unit vertical pressure under the footing<br>         w = weight of soil per cubic meter<br>          = angle of repose <br>    In situation where the pond is a non-compartment type contrary to the one considered for this project but yet the same or similar size with the design model, it is recommended that columns be <br>

FISH POND RECOMMENDATIONS

CONCLUSIONS AND RECOMMENDATIONS 5.1 Conclusions The following conclusions were drawn after the design analysis: Concrete filled h...

FISH POND EVALUATION PROCEDURE

Executive mai Doya 0 AGRICULTURAL ENGINEERING 5:50 AM

<h2>
Fish Pond Evaluation</h2>
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<u><a href="https://www.blogger.com/null" name="ch2.1"><b><span style="font-family: "Times New Roman"; font-size: 13.5pt; mso-fareast-font-family: "Times New Roman";">Criteria used for fish pond evaluation</span></b></a></u><b><span style="font-family: "Times New Roman"; font-size: 13.5pt; mso-fareast-font-family: "Times New Roman";"></span></b></h2>
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 1. WATER SUPPLY<br><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;"></span></i></h3>
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<span style="font-family: "Times New Roman";">Adequate supply of good quality of fresh
and salt-water must be available year round in the site. Good quality water
suitable for fish culture is rich in oxygen, nutrients and free from
pollutants.</span></div>
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<span style="font-family: "Times New Roman";">Freshwater is important for mixing with
sea water to maintain salinity level especially in the dry season when
evaporation is rapid. Freshwater is also necessary for the daily use of the
workers in the fish farm.</span></div>
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<span style="font-family: "Times New Roman";">2. SOIL CHARACTERISTICS </span></h3>
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<a href="https://www.blogger.com/null" name="ch2.1.3"><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;"></span></i></a><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;"></span></i></h3>
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<span style="font-family: "Times New Roman";">Many soil characteristics, especially
those related to texture, determine its suitability for fishpond purposes. Soil
texture refers to the relative proportion of sand, silt and clay content of the
soil. Table 1 below shows the different soil classification based from the
U.S. Department of Agriculture Classification System.</span></div>
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<b><span style="font-family: "Times New Roman";">Table 1<br>
Texture and textural name of the three main types of soil</span></b><span style="font-family: "Times New Roman";"></span></div>
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<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Class</span></b></div>
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<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Permeability</span></b></div>
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<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Compressibility</span></b></div>
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<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Compaction</span></b></div>
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<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Suitability</span></b></div>
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<tr style="mso-yfti-irow: 1;">
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Clay</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Impervious</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Medium</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Fair to good</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Excellent</span></div>
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<tr style="mso-yfti-irow: 2;">
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Sandy clay</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Impervious</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Low</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Loamy</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Semi-pervious</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">High</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Fair to very poor</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Fair</span></div>
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<tr style="mso-yfti-irow: 4;">
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  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">to impervious</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">high</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Silty</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Semi-pervious</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Medium</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good to very poor</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Poor</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Sandy</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">to impervious</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">to high</span></div>
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  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Peaty</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Pervious</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">High</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good</span></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Poor</span></div>
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  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Peaty</span></div>
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<br></div>
</td>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Negligible</span></div>
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<br></div>
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<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Very poor</span></div>
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</tbody></table>
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<a href="https://www.blogger.com/null" name="Fig2.3"></a><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-no-proof: yes;"></span><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";"></span></div>
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<h2>
 </h2>
<h2>
TOPOGRAPHY OF FISH POND SITE </h2>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Topography refers to the “lay of the
land” or the changes in the surface elevations of the ground whether flat,
rolling or sloping, undulating, and hilly. Fishpond design, layout and
specifications are made largely in accordance with the land topography.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<br></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">A suitable site for fishpond has a
topography that can be converted into a pond economically. The cost of
construction can be greatly reduced if the surface features of the land are
used to advantage.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Flat coastal swamplands whose elevation
are within the range of ideal pond bottom elevation are preferred for
brackishwater pond culture. In such areas, excavation or filling are at a
minimum, if any. Sites with rolling topography or those with elevations varying
from lower than MLLW (00 tidal datum) to 4–5 m high must be avoided as these
will be too costly to level (de los Santos, 1980).</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Denila (1980) describes four zones in the
coastal edge as probable sites for fishpond </span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(a) <i>Zone A</i>. Marginal lands along
edges usually planted to lowland rice but generally unproductive due to salt
water seepage can be converted into fishpond by lowering the elevation through
excavation. These are usually productive as fishponds because of good soil
quality. The cost of excavation can make these areas relatively more expensive
to develop due to their high elevation.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(b) <i>Zone B</i>. The elevation is
generally high with occasional earth mounds along the edges but can be reached
by tides. High dikes not necessary but development cost may be expensive if a
big portion of the area needs excavation.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(c) <i>Zone C</i>. This area is within
the ideal range of pond bottom elevation, thus excavation cost is less.
However, extreme acidity may occur because of the presence of vegetation that
contributes to acidity.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(d) <i>Zone D</i>. The elevation is low
or just a little higher than the 00 datum (MLLW). It is very exposed to wave
action which may require expensive big dikes and wave protection structures. No
acidity problem, hence, may be ideal for shrimp culture.</span></div>
<div class="MsoNormal" style="margin-top: 2.0pt; mso-outline-level: 4; mso-pagination: widow-orphan lines-together; page-break-after: avoid;">
<br></div>
<div class="MsoNormal" style="margin-top: 2.0pt; mso-outline-level: 4; mso-pagination: widow-orphan lines-together; page-break-after: avoid;">

</div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; mso-outline-level: 3;">
<a href="https://www.blogger.com/null" name="ch2.1"><b><span style="font-family: "Times New Roman"; font-size: 13.5pt; mso-fareast-font-family: "Times New Roman";">2.1 Criteria used</span></b></a><b><span style="font-family: "Times New Roman"; font-size: 13.5pt; mso-fareast-font-family: "Times New Roman";"></span></b></div>
<div class="MsoNormal" style="margin-top: 2.0pt; mso-outline-level: 4; mso-pagination: widow-orphan lines-together; page-break-after: avoid;">
<a href="https://www.blogger.com/null" name="ch2.1.1"><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;">2.1.1 Water supply</span></i></a><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;"></span></i></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Adequate supply of good quality of fresh
and salt-water must be available year round in the site. Good quality water
suitable for fish culture is rich in oxygen, nutrients and free from
pollutants.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Freshwater is important for mixing with
sea water to maintain salinity level especially in the dry season when
evaporation is rapid. Freshwater is also necessary for the daily use of the
workers in the fish farm.</span></div>
<div class="MsoNormal" style="margin-top: 2.0pt; mso-outline-level: 4; mso-pagination: widow-orphan lines-together; page-break-after: avoid;">
<br></div>
<h3 class="MsoNormal" style="margin-top: 2.0pt; mso-outline-level: 4; mso-pagination: widow-orphan lines-together; page-break-after: avoid;">
<a href="https://www.blogger.com/null" name="ch2.1.3"><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;">SOIL CHARACTERISTICS OF FISH PONDS</span></i></a><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;"></span></i></h3>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Many soil characteristics, especially
those related to texture, determine its suitability for fishpond purposes. Soil
texture refers to the relative proportion of sand, silt and clay content of the
soil. Table 3 below shows the different soil classification based from the
U.S. Department of Agriculture Classification System.</span></div>
<div align="center" class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; text-align: center;">
<b><span style="font-family: "Times New Roman";">Table 3<br>
Texture and textural name of the three main types of soil</span></b><span style="font-family: "Times New Roman";"></span></div>
<div align="center">

<table border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="mso-cellspacing: 0cm; mso-padding-alt: 2.0pt 2.0pt 2.0pt 2.0pt; mso-yfti-tbllook: 1184; width: 90%px;">
 <tbody>
<tr style="mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div align="center" class="MsoNormal" style="text-align: center;">
<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Class</span></b></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div align="center" class="MsoNormal" style="text-align: center;">
<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Permeability</span></b></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div align="center" class="MsoNormal" style="text-align: center;">
<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Compressibility</span></b></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div align="center" class="MsoNormal" style="text-align: center;">
<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Compaction</span></b></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div align="center" class="MsoNormal" style="text-align: center;">
<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Suitability</span></b></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 1;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Clay</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Impervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Medium</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Fair to good</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Excellent</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 2;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Sandy clay</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Impervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Low</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 3;">
  <td rowspan="2" style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;" valign="top">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Loamy</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Semi-pervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">High</span></div>
</td>
  <td rowspan="2" style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;" valign="top">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Fair to very poor</span></div>
</td>
  <td rowspan="2" style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;" valign="top">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Fair</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 4;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">to impervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">high</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 5;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Silty</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Semi-pervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Medium</span></div>
</td>
  <td rowspan="2" style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;" valign="top">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good to very poor</span></div>
</td>
  <td rowspan="2" style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;" valign="top">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Poor</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 6;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Sandy</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">to impervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">to high</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 7;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Peaty</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Pervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">High</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Poor</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 8; mso-yfti-lastrow: yes;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Peaty</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<br></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Negligible</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<br></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Very poor</span></div>
</td>
 </tr>
</tbody></table>
</div>
<div align="center" class="MsoNormal" style="text-align: center;">
<a href="https://www.blogger.com/null" name="Fig2.3"></a><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-no-proof: yes;"></span><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";"></span></div>
<div class="MsoNormal">
<br></div>
<h2 class="MsoNormal" style="margin-top: 2.0pt; mso-outline-level: 4; mso-pagination: widow-orphan lines-together; page-break-after: avoid;">
<i>TOPOGRAPHY OF FISH POND SITE</i><br><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;"></span></i></h2>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Topography refers to the “lay of the
land” or the changes in the surface elevations of the ground whether flat,
rolling or sloping, undulating, and hilly. Fishpond design, layout and
specifications are made largely in accordance with the land topography.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">A suitable site for fishpond has a
topography that can be converted into a pond economically. The cost of
construction can be greatly reduced if the surface features of the land are
used to advantage.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Flat coastal swamplands whose elevation
are within the range of ideal pond bottom elevation are preferred for
brackishwater pond culture. In such areas, excavation or filling are at a
minimum, if any. Sites with rolling topography or those with elevations varying
from lower than MLLW (00 tidal datum) to 4–5 m high must be avoided as these
will be too costly to level (de los Santos, 1980).</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Denila (1980) describes four zones in the
coastal edge as probable sites for fishpond (Fig. 2.7).</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(a) <i>Zone A</i>. Marginal lands along
edges usually planted to lowland rice but generally unproductive due to salt
water seepage can be converted into fishpond by lowering the elevation through
excavation. These are usually productive as fishponds because of good soil
quality. The cost of excavation can make these areas relatively more expensive
to develop due to their high elevation.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(b) <i>Zone B</i>. The elevation is
generally high with occasional earth mounds along the edges but can be reached
by tides. High dikes not necessary but development cost may be expensive if a
big portion of the area needs excavation.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(c) <i>Zone C</i>. This area is within
the ideal range of pond bottom elevation, thus excavation cost is less.
However, extreme acidity may occur because of the presence of vegetation that
contributes to acidity.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(d) <i>Zone D</i>. The elevation is low
or just a little higher than the 00 datum (MLLW). It is very exposed to wave
action which may require expensive big dikes and wave protection structures. No
acidity problem, hence, may be ideal for shrimp culture.</span></div>
<div class="MsoNormal" style="margin-top: 2.0pt; mso-outline-level: 4; mso-pagination: widow-orphan lines-together; page-break-after: avoid;">
<a href="https://www.blogger.com/null" name="ch2.1.5"><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;">2.1.5 Type and density of vegetation</span></i></a><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;"></span></i></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Coastal fishponds in the tropical and
sub-tropical zones are constructed on tidal lands, river estuaries, bays and
sheltered coasts. The vegetation present in these areas are varied depending on
the land elevation and soil type. However, mangrove trees pose serious concern
to fishpond development because of their extensive rooting system.</span></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<a href="https://www.blogger.com/null" name="Fig2.7"></a><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-no-proof: yes;"><img alt="ig. 2.7" height="266" src="file://localhost/Users/gedaliahtechnologies/Library/Group%20Containers/UBF8T346G9.Office/msoclip1/01/clip_image004.png" width="451"></span><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";"></span></div>
<div align="center" class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; text-align: center;">
<span style="font-family: "Times New Roman";">Fig. 2.7
The four zones in typical swamps as probable sites for fishpond (After Denila,
1980)</span></div>
<h4>
<a href="https://www.blogger.com/null" name="ch2.1.6"><span style="mso-fareast-font-family: "Times New Roman";">2.1.6
Climatic and watershed conditions around the site</span></a><span style="mso-fareast-font-family: "Times New Roman";"></span></h4>
The climatic factors largely affecting site selection and fishpond design
are wind and rainfall. The direction of prevailing wind is reckoned with in
designing the layout of fishponds as it generates erosive wave action against
the dikes. The wind energy also causes natural water circulation and aeration
in the pond. For rainfall information, maximum intensity, duration, frequency
and annual distribution within the watershed are important as these are
associated with flooding that would affect the site.<br>

The land area that surrounds or lies above the site is referred to as a
watershed. This drains its collected surface runoff through a river, river
system or body of water causing flood water which could affect the site. The
volume of flood water or runoff are affected by the rainfall and soil
characteristics, type of vegetative cover, topography, and area of the
watershed. Much higher rate of runoff can be expected in a watershed that has high
rainfall intensity and duration, clay or heavy-textured soil covered with less
vegetation or grassland, high slopes and covering large area than a watershed
characterized with low rainfall intensity and short duration, loamy or
coarse-textured soil that is forested with flat or gently rolling slope and
small area.<br>

The pattern and recurrence of maximum height of flood waters in the site
must be determined. These information can be obtained from the rainfall or
flood records of appropriate agency for each country. It is common, however,
that the sites are located in remote areas where such records may not be
available. In this situation, rough information on flood may be obtained from
knowledgeable residents who have seen the recurrence of floods for years in the
area.<br>

The design of fish farm should be based on a flood height with recurrence
interval of 10–15 years. Longer recurrence interval of 25 or 50 years means
much higher flood level and hence, much bigger dikes and structures which makes
the design uneconomical or impractical. It would be more economical to repair
damaged fishponds (designed for 10–15 years flood) during the sudden occurrence
of say 25 years or longer term floods than to design the entire farm for such
floods.<br>

<h4>
<a href="https://www.blogger.com/null" name="ch2.1.7"><span style="mso-fareast-font-family: "Times New Roman";">2.1.7
Other criteria</span></a><span style="mso-fareast-font-family: "Times New Roman";"></span></h4>
There are other factors which are significant in fishpond site selection.
These are equally as important as those previously mentioned and likewise
require the same careful evaluation during the survey.<br>

<div style="margin-left: 36.0pt; mso-list: l1 level1 lfo1; tab-stops: list 36.0pt; text-indent: -18.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;">a.<span style="font: 7.0pt "Times New Roman";">         
</span></span></span><i>Accessibility</i>. This is important for the
transport of construction equipment and material, and for production inputs
required for daily operations. Transporting costs can considerably increase if
materials are manually carried through long distances. It is better if the site
is accessible throughout the year by means of land and water.</div>
<div style="margin-left: 36.0pt; mso-list: l1 level1 lfo1; tab-stops: list 36.0pt; text-indent: -18.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;">b.<span style="font: 7.0pt "Times New Roman";">        
</span></span></span><i>Availability of labour</i>. The cheapest
sources of labour are those which can be provided by the local residents, or
people living within or near the area. It is important that the customs and
tradition of local labourers are known. The pattern of labour distribution and
utilization should be considered as this is important in preparing the calendar
of activities. In the Philippines, it is generally difficult to obtain enough
labour during the rice planting and harvesting season or during milling season
for sugarcane.</div>
<div style="margin-left: 36.0pt; mso-list: l1 level1 lfo1; tab-stops: list 36.0pt; text-indent: -18.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;">c.<span style="font: 7.0pt "Times New Roman";">         
</span></span></span><i>Availability and cost of material</i>. In
fishpond production, it is important that critical production inputs such as
fishseeds, fertilizers, pesticides and other related materials are readily
available when needed. For some inputs, especially inorganic fertilizers, the
supply is restricted and the cost is uncontrolled for non-agricultural uses.
Other inputs like organic manures are difficult to obtain, or may be available
only at certain times of the year. If purchase in bulk is necessary, then
storage space must be available. If material is to be imported, restrictions
and corresponding costs must be known.</div>
<div style="margin-left: 36.0pt; mso-list: l1 level1 lfo1; tab-stops: list 36.0pt; text-indent: -18.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;">d.<span style="font: 7.0pt "Times New Roman";">        
</span></span></span><i>Availability of marketing outlets and prices</i>.
Aquaculture products are highly perishable. Immediately upon harvest, products
must be disposed of to maintain good quality and for better prices. If
marketing outlets are located at a distance, larger quantities must be
harvested and transported requiring some post-harvest marketing practices. If
so, then the required support facilities especially ice-making plants must be
available.</div>
<div style="margin-left: 36.0pt; mso-list: l1 level1 lfo1; tab-stops: list 36.0pt; text-indent: -18.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;">e.<span style="font: 7.0pt "Times New Roman";">         
</span></span></span><i>Availability of credit and technical
assistance</i>. Fishpond operations require high initial capital investment. In
this respect, credit at reasonable terms play a major role in providing the
needed cash outlays.</div>
<div style="margin-left: 36.0pt;">
Technical assistance may be obtained from
government extension services, public or private university research stations
and lending institutions. The services rendered by these agencies are important
especially in cases of emergency.</div>
<div style="margin-left: 36.0pt; mso-list: l1 level1 lfo1; tab-stops: list 36.0pt; text-indent: -18.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;">f.<span style="font: 7.0pt "Times New Roman";">           
</span></span></span><i>Pattern of land and water use</i>. It is
important to assess the pattern of land and water use in the area to determine
the impact of this on the project. Activities such as navigation, fishing,
industries, public utilities, recreation and nursery areas must be included in
the overall assessment. It is best that a complementary rather than competitive
relationship between these various uses and the project be established.</div>
<div style="margin-left: 36.0pt; mso-list: l1 level1 lfo1; tab-stops: list 36.0pt; text-indent: -18.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;">g.<span style="font: 7.0pt "Times New Roman";">        
</span></span></span><i>Peace and order situation</i>. Good peace and
order conditions at site are favourable for both public and private interests.</div>
<h3>
<a href="https://www.blogger.com/null" name="ch2.2"><span style="mso-fareast-font-family: "Times New Roman";">2.2
Making the decision</span></a><span style="mso-fareast-font-family: "Times New Roman";"></span></h3>
The success of coastal fishpond operations depends not only on the general
site suitability for fish production but also on other related factors such as
input and labour availability, accessibility, marketing considerations and
others. Site selection not only involves the determination of desirable
physical, chemical and biological factors. It is also important in providing
valuable information in the preparation of the overall design and layout of the
facility, engineering modifications to be made and the choice of management
practices appropriate for the given site.<br>

It is important to remember that there is no site that possesses all the
desirable characteristics for fishpond operation. Moreover, no two sites are
exactly identical with one another. Hence, the degree of suitability of various
sites evaluated vary from one area to another.<br>

<h4>
<a href="https://www.blogger.com/null" name="ch2.2.1"><span style="mso-fareast-font-family: "Times New Roman";">2.2.1
Method of evaluation</span></a><span style="mso-fareast-font-family: "Times New Roman";"></span></h4>
The evaluation of the suitability of fish farm sites involves a detailed
survey of both technical and non-technical aspects, and the processing of
information gathered in order to make the final selection.<br>

<div style="margin-left: 36.0pt; mso-list: l0 level1 lfo2; tab-stops: list 36.0pt; text-indent: -18.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;">a.<span style="font: 7.0pt "Times New Roman";">         
</span></span></span><i>The survey</i>. If possible, the survey
should be comprehesive to cover aquacultural, ecological, engineering,
socio-economic, management and financial aspects. As a standard practice at
least two surveys should be conducted during the year—one each during the dry
and rainy seasons. It is important to evaluate the prevailing conditions for
different seasons because there are factors that change at different times of
the year. A wrong judgement could be made in the selection if only one survey
is conducted.</div>
<div style="margin-left: 36.0pt;">
Conducting the survey can be a costly, laborious
and time-consuming exercise if the proper steps, procedures and preparation are
taken for granted. Adisukresno (1982) recommends the following to save money,
time and effort:</div>
<div style="margin-left: 72.0pt; mso-list: l0 level2 lfo2; mso-text-indent-alt: -18.0pt; tab-stops: list 72.0pt; text-indent: -72.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;"><span style="font: 7.0pt "Times New Roman";">                                               
</span>i.<span style="font: 7.0pt "Times New Roman";">                 
</span></span></span>Sufficient and complete questionnaires or forms
should be prepared before leaving for the survey;</div>
<div style="margin-left: 72.0pt; mso-list: l0 level2 lfo2; mso-text-indent-alt: -18.0pt; tab-stops: list 72.0pt; text-indent: -72.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;"><span style="font: 7.0pt "Times New Roman";">                                            
</span>ii.<span style="font: 7.0pt "Times New Roman";">                 
</span></span></span>Questionnaries must be properly and completely
accomplished during the survey;</div>
<div style="margin-left: 72.0pt; mso-list: l0 level2 lfo2; mso-text-indent-alt: -18.0pt; tab-stops: list 72.0pt; text-indent: -72.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;"><span style="font: 7.0pt "Times New Roman";">                                         
</span>iii.<span style="font: 7.0pt "Times New Roman";">                 
</span></span></span>An itinerary or travel schedule should be
prepared;</div>
<div style="margin-left: 72.0pt; mso-list: l0 level2 lfo2; mso-text-indent-alt: -18.0pt; tab-stops: list 72.0pt; text-indent: -72.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;"><span style="font: 7.0pt "Times New Roman";">                                         
</span>iv.<span style="font: 7.0pt "Times New Roman";">                 
</span></span></span>Only trained or capable personnel should conduct
the survey;</div>
<div style="margin-left: 72.0pt; mso-list: l0 level2 lfo2; mso-text-indent-alt: -18.0pt; tab-stops: list 72.0pt; text-indent: -72.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;"><span style="font: 7.0pt "Times New Roman";">                                            
</span>v.<span style="font: 7.0pt "Times New Roman";">                 
</span></span></span>Needed field equipment should always be put
together and brought along;</div>
<div style="margin-left: 72.0pt; mso-list: l0 level2 lfo2; mso-text-indent-alt: -18.0pt; tab-stops: list 72.0pt; text-indent: -72.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;"><span style="font: 7.0pt "Times New Roman";">                                         
</span>vi.<span style="font: 7.0pt "Times New Roman";">                 
</span></span></span>A list of people to be the met and purpose of
meeting should be prepared ahead of time.</div>
<div style="margin-left: 36.0pt; mso-list: l0 level1 lfo2; tab-stops: list 36.0pt; text-indent: -18.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;">b.<span style="font: 7.0pt "Times New Roman";">        
</span></span></span><i>Processing of information</i>. Data and
information collected during the survey are combination of quantitative and
qualitative; thus, it is very difficult to arrive at a general decision. The
most commonly used method of deciding the suitability of sites from among a
number of prospective sites surveyed is the point and ranking system.</div>
<div style="margin-left: 36.0pt; mso-list: l0 level1 lfo2; tab-stops: list 36.0pt; text-indent: -18.0pt;">
<span style="mso-fareast-font-family: "Times New Roman";"><span style="mso-list: Ignore;">c.<span style="font: 7.0pt "Times New Roman";">         
</span></span></span><i>Applying the point and ranking system</i>.
Under this system, all data and information are transferred into numbers or
assigned numerical points or scores. The scoring could be from 1 to 10 or from
1 to 100. A site with the most desirable characteristic for a certain criterion
is assigned the highest score, the lower the value, the less ideal or desirable
site becomes and vice-versa. For example, in evaluating the accessibility, if a
road leads right into the central area, a score of 10 can be given to this
site; if reached within walking distance, 9; and if reached along across a
river or creek, 8 or less. With regard to the type of vegetation, presence of <i>Nypa</i>
sp. can be ranked lowest; mangrove with <i>Avicennia</i> sp. can be ranked
highest, and so on.</div>
<div class="MsoNormal">
<br></div>
<style>

</style>

<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; mso-outline-level: 3;">
<a href="https://www.blogger.com/null" name="ch2.1"><b><span style="font-family: "Times New Roman"; font-size: 13.5pt; mso-fareast-font-family: "Times New Roman";">2.1 Criteria used</span></b></a><b><span style="font-family: "Times New Roman"; font-size: 13.5pt; mso-fareast-font-family: "Times New Roman";"></span></b></div>
<div class="MsoNormal" style="margin-top: 2.0pt; mso-outline-level: 4; mso-pagination: widow-orphan lines-together; page-break-after: avoid;">
<a href="https://www.blogger.com/null" name="ch2.1.1"><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;">2.1.1 Water supply</span></i></a><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;"></span></i></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Adequate supply of good quality of fresh
and salt-water must be available year round in the site. Good quality water
suitable for fish culture is rich in oxygen, nutrients and free from
pollutants.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Freshwater is important for mixing with
sea water to maintain salinity level especially in the dry season when
evaporation is rapid. Freshwater is also necessary for the daily use of the
workers in the fish farm.</span></div>
<div class="MsoNormal" style="margin-top: 2.0pt; mso-outline-level: 4; mso-pagination: widow-orphan lines-together; page-break-after: avoid;">
<a href="https://www.blogger.com/null" name="ch2.1.3"><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;">2.1.3 Soil characteristics</span></i></a><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;"></span></i></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Many soil characteristics, especially
those related to texture, determine its suitability for fishpond purposes. Soil
texture refers to the relative proportion of sand, silt and clay content of the
soil. Table 2.2 below shows the different soil classification based from the
U.S. Department of Agriculture Classification System.</span></div>
<div align="center" class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; text-align: center;">
<b><span style="font-family: "Times New Roman";">Table
2.2<br>
Texture and textural name of the three main types of soil</span></b><span style="font-family: "Times New Roman";"></span></div>
<div align="center">

<table border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="mso-cellspacing: 0cm; mso-padding-alt: 2.0pt 2.0pt 2.0pt 2.0pt; mso-yfti-tbllook: 1184; width: 90%px;">
 <tbody>
<tr style="mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div align="center" class="MsoNormal" style="text-align: center;">
<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Class</span></b></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div align="center" class="MsoNormal" style="text-align: center;">
<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Permeability</span></b></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div align="center" class="MsoNormal" style="text-align: center;">
<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Compressibility</span></b></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div align="center" class="MsoNormal" style="text-align: center;">
<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Compaction</span></b></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div align="center" class="MsoNormal" style="text-align: center;">
<b><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Suitability</span></b></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 1;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Clay</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Impervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Medium</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Fair to good</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Excellent</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 2;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Sandy clay</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Impervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Low</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 3;">
  <td rowspan="2" style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;" valign="top">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Loamy</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Semi-pervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">High</span></div>
</td>
  <td rowspan="2" style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;" valign="top">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Fair to very poor</span></div>
</td>
  <td rowspan="2" style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;" valign="top">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Fair</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 4;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">to impervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">high</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 5;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Silty</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Semi-pervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Medium</span></div>
</td>
  <td rowspan="2" style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;" valign="top">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good to very poor</span></div>
</td>
  <td rowspan="2" style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;" valign="top">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Poor</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 6;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Sandy</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">to impervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">to high</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 7;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Peaty</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Pervious</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">High</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Good</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Poor</span></div>
</td>
 </tr>
<tr style="mso-yfti-irow: 8; mso-yfti-lastrow: yes;">
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Peaty</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<br></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Negligible</span></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<br></div>
</td>
  <td style="padding: 2.0pt 2.0pt 2.0pt 2.0pt;">
  <div class="MsoNormal">
<span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";">Very poor</span></div>
</td>
 </tr>
</tbody></table>
</div>
<div align="center" class="MsoNormal" style="text-align: center;">
<a href="https://www.blogger.com/null" name="Fig2.3"></a><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-no-proof: yes;"><img alt="ig. 2.3" height="344" src="file://localhost/Users/gedaliahtechnologies/Library/Group%20Containers/UBF8T346G9.Office/msoclip1/01/clip_image002.png" width="377"></span><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";"></span></div>
<div class="MsoNormal">
<br></div>
<div class="MsoNormal" style="margin-top: 2.0pt; mso-outline-level: 4; mso-pagination: widow-orphan lines-together; page-break-after: avoid;">
<a href="https://www.blogger.com/null" name="ch2.1.4"><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;">2.1.4 Topography of the site</span></i></a><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;"></span></i></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Topography refers to the “lay of the
land” or the changes in the surface elevations of the ground whether flat,
rolling or sloping, undulating, and hilly. Fishpond design, layout and
specifications are made largely in accordance with the land topography.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">A suitable site for fishpond has a
topography that can be converted into a pond economically. The cost of
construction can be greatly reduced if the surface features of the land are
used to advantage.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Flat coastal swamplands whose elevation
are within the range of ideal pond bottom elevation are preferred for
brackishwater pond culture. In such areas, excavation or filling are at a
minimum, if any. Sites with rolling topography or those with elevations varying
from lower than MLLW (00 tidal datum) to 4–5 m high must be avoided as these
will be too costly to level (de los Santos, 1980).</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Denila (1980) describes four zones in the
coastal edge as probable sites for fishpond (Fig. 2.7).</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(a) <i>Zone A</i>. Marginal lands along
edges usually planted to lowland rice but generally unproductive due to salt
water seepage can be converted into fishpond by lowering the elevation through
excavation. These are usually productive as fishponds because of good soil
quality. The cost of excavation can make these areas relatively more expensive
to develop due to their high elevation.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(b) <i>Zone B</i>. The elevation is
generally high with occasional earth mounds along the edges but can be reached
by tides. High dikes not necessary but development cost may be expensive if a
big portion of the area needs excavation.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(c) <i>Zone C</i>. This area is within
the ideal range of pond bottom elevation, thus excavation cost is less.
However, extreme acidity may occur because of the presence of vegetation that
contributes to acidity.</span></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">(d) <i>Zone D</i>. The elevation is low
or just a little higher than the 00 datum (MLLW). It is very exposed to wave
action which may require expensive big dikes and wave protection structures. No
acidity problem, hence, may be ideal for shrimp culture.</span></div>
<div class="MsoNormal" style="margin-top: 2.0pt; mso-outline-level: 4; mso-pagination: widow-orphan lines-together; page-break-after: avoid;">
<a href="https://www.blogger.com/null" name="ch2.1.5"><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;">2.1.5 Type and density of vegetation</span></i></a><i><span style="color: #2e74b5; font-family: "Calibri Light"; mso-ascii-theme-font: major-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-theme-font: major-bidi; mso-fareast-font-family: "Times New Roman"; mso-hansi-theme-font: major-latin; mso-themecolor: accent1; mso-themeshade: 191;"></span></i></div>
<div class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto;">
<span style="font-family: "Times New Roman";">Coastal fishponds in the tropical and
sub-tropical zones are constructed on tidal lands, river estuaries, bays and
sheltered coasts. The vegetation present in these areas are varied depending on
the land elevation and soil type. However, mangrove trees pose serious concern
to fishpond development because of their extensive rooting system.</span></div>
<div align="center" class="MsoNormal" style="text-align: center;">
<a href="https://www.blogger.com/null" name="Fig2.7"></a><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-no-proof: yes;"><img alt="ig. 2.7" height="266" src="file://localhost/Users/gedaliahtechnologies/Library/Group%20Containers/UBF8T346G9.Office/msoclip1/01/clip_image004.png" width="451"></span><span style="font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman";"></span></div>
<div align="center" class="MsoNormal" style="mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; text-align: center;">
<span style="font-family: "Times New Roman";">Fig. 2.7
The four zones in typical swamps as probable sites for fishpond (After Denila,
1980)</span></div>
<h4>
<a href="https://www.blogger.com/null" name="ch2.1.6"><span style="mso-fareast-font-family: "Times New Roman";">2.1.6
Climatic and watershed conditions around the site</span></a><span style="mso-fareast-font-family: "Times New Roman";"></span></h4>
The climatic factors largely affecting site selection and fishpond design
are wind and rainfall. The direction of prevailing wind is reckoned with in
designing the layout of fishponds as it generates erosive wave action against
the dikes. The wind energy also causes natural water circulation and aeration
in the pond. For rainfall information, maximum intensity, duration, frequency
and annual distribution within the watershed are important as these are
associated with flooding that would affect the site.<br>

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