Fishpond Engineering is the science of planning, designing and constructing ponds including water control structures. Although not entirely new in the Fish Farm industry, it has gained international acceptance and plays an important role for the efficiency of the farm management as well as in attaining higher farm production. Fishpond Engineering takes into consideration most especially the physical structures and economy of construction based on the proper engineering procedure and application.
2.SITE SELECTION AND EVALUATION OF EXISTING AREAS
2.1 Water Supply
Water supply is the first and most important factor to consider in the suitability of a fishpond site. Usually, water supply comes from a river, a creek or from the sea. It must meet the quality and quantity requirement of the pond system throughout the year. Water quality is affected by the physical, the chemical, and the biological parameters. Such parameters are affected by the 1) by-products and wastes resulting from urbanization, 2) agricultural pollutants such as pesticides and fertilizers, 3) industrial wastes from pulp mills, sugar, oil refineries, and textile plants, 4) radio-active wastes, 5) oil pollution arising navigational activities, uncontrolled spillage, and oil exploration. Some of these parameters are discussed in detail under fishpond management. Poor quality water sometimes causes the fouling of gates, screens or metal pipes. This happens when heavy dredging is being conducted in an area. Heavy dredging increases turbidity and causes the release of organic substances embedded in the soil. Once these organic substances are released, they use up oxygen causing high biological oxygen demand (BOD). Higher BOD causes oxygen depletion which in turn makes the water foul. Similar conditions also occur during floods. Water supply in tide-fed farms must be adequate especially during some months of the year when the height of high water is at minimum. This problem can be solved by proper gate design and by the use of pumps. The rate of volume flow of nearby tidal stream needs also to be considered; measurement is made during the dry stream flow and during floods. The data obtained give the developer the minimum and maximum rates of discharge. These are important requirements in fish farm design. For details, refer to Annex I.
2.2 Tidal Characteristic and Ground Elevation
The suitability of a tide-fed area for a “bangus” fishpond project depends on the relationship between the tidal characteristic of the area and its ground elevation. The only free source of energy that could be tapped for flooding a brackishwater coastal pond is tidal energy which is available once or twice a day depending on geographical location. Five reference stations in the Philippines exhibit five peculiarly different patterns during some months of the year. Figure 1 shows in a graphical form the relationship of natural ground elevation to tidal characteristic. Tables 1 and 2 show such relationships as they are applicable to the six stations of reference. [pic]
Figure 1 - Suitability of Proposed Fishpond Site Based on Tidal Characteristic and Ground Elevation. |LOCALITY |Elevations in Meters Above Mean Lower Low H20 | | |Mean High Water (MHW) |Mean Sea Level (MSL) |Mean Low Water (MLW) | |Pier 13, South Harbor, Manila |0.872 |0.479 |0.104 | |Pier 2, Cebu City |1.250 |0.722 |0.183 | |Legaspi Port, Legaspi City |1.329 |0.744 |0.165 | |Sta. Ana Port Davao City |1.405 |0.753 |0.101 | |Port of Poro, San Fernando, La Union |-...