|Better Farming Series 35 - Better Freshwater Fish Farming: Further Improvement (FAO, 1986, 61 p.)|
|Bringing water to your ponds|
42. If the stream that supplies your water is not much higher than your ponds, it may be difficult to get the water to run down when you want to fill them.
43. By building a barrage, you can raise the level of the stream so that water will run down more easily into your fish- ponds.
barrage of tree branches
44. You can build a simple barrage (using a woven mesh of tree branches like the one shown above). You can also use loose stones or rocks or logs set into the stream bottom.
45. A barrage does not hold back all of the water that runs down the stream. Depending on how it is built, some of the water will be held back and some of the water will flow through or over the barrage.
46. If the tree branches, logs or rocks are placed tightly together, the water level behind the barrage will be higher.
47. If the tree branches, logs or rocks are not placed so tightly, the water level behind the barrage will be lower.
48. If you build a barrage and too much water flows through, you can hold back more water by putting more branches, logs or rocks on the barrage.
49. After you have built a barrage and the water behind it has reached its highest level, you will need to dig a supply ditch to take the water to your ponds.
Dig a supply ditch
50. Begin by digging the supply ditch just behind the barrage where the water is deepest. However, dig it in such a way that the water in the stream will not flow into the ditch.
51. You can do this by starting the supply ditch about 1 metre away from the edge of the water. When you are ready to fill your ponds, you can remove this 1- metre strip (see Item 69) and the water will flow into the ditch.
Remove the strip
53. The ditch should have very little slope. You can use a straight board and a mason's level to help you to dig your ditch.
54. When you reach your highest pond, the ditch should be near the inlet. Continue to dig your water- supply ditch until you reach your lowest pond.
55. When the supply ditch is past the end of the lowest pond, continue to dig it downhill for about 10 metres. Then bring it slowly to the surface. That way, when you fill your ponds, any extra water will flow out at ground level.
56. Now, dig a small ditch to connect the inlet of each pond to the supply ditch.
Continue supply ditch
57. You will also need to dig one or more ditches 10 take the water back to the stream when you empty your ponds.
58. These are called return ditches and how you dig them will depend on how your ponds are placed and how near they are to the stream. Try to choose the easiest and shortest path to take the water back to the stream.
59. If your ponds are near the stream, the easiest way to get the water back is to dig a return ditch from the outlet of each pond straight to the stream. You can also use one ditch for two ponds.
60. If your ponds are not near the stream or if you cannot dig a ditch straight to the stream, dig only one return ditch along the outlet side of your ponds, which can take all the water from all the ponds.
61. Start this ditch at the outlet of your highest pond. The ditch should run past the outlet of the lowest pond and then back to the stream.
62. Now, dig a small ditch to connect the outlet of each pond to the return ditch.
63. When you have built your ditches, you will need a way to control the flow of water from the stream into your supply ditch and from your supply ditch into the inlet ditches of each of your ponds.
From the stream into your supply ditch
64. To control the flow of water into your supply ditch, you can build a sluice somewhat like the one you learned to build for an inlet (see pages 14 and 15 in this booklet).
65. However, instead of one slot in each wall, this sluice will have three slots in each wall. Two sets of slots are for wooden boards and the third set is for a screen to keep out wild fish.
66. Build this sluice at the top of the supply ditch just behind the 1- metre strip of soil that you left at the edge of the water when you began digging the ditch.
Digging the ditch
67. The drawing at the top of the next page shows you how to build a wooden sluice for the supply ditch at the stream.
Building a wooden sluice for the supply ditch
68. Pack the space between the boards with good clay soil to keep the water from leaking through. However, do not put in the screen until you are ready to use the sluice. Put it aside so that it will not be broken.
Put the screen
69. Now, remove the 1- metre strip of soil you left at the edge of the stream. The water will flow into the ditch up to the wooden planks in the sluice.
Remove the strip
From the supply ditch into your ponds
70. You can build a smaller sluice to control the flow of water into your ponds. With this sluice you need only one set of boards. The drawing below shows you how.
Building a wooden sluice for a pond inlet
71. You will need one sluice for each of your ponds. Build them at the lower corners of each inlet ditch. The drawing below shows you where to put this kind of sluice.
Put the boards in place
72. Slide wooden boards into the slots of this sluice to send all the water into a pond, or take them out to let all the water flow farther down the supply ditch into another pond.
73. You can also adjust the boards in each sluice so that part of the water will go into one pond and the rest will flow down 10 feed the other ponds.
74. When you have finished digging your supply and return ditches and have built all of the sluices, you are ready to fill your ponds.
Ponds are filled one by one. Items 75 and 77 will tell you, step by step, how to begin filling your ponds. The large drawing on pages 38 and 39 will also help you to understand the various steps.
75. To fill the first pond do the following
· make sure that the outlet of the first pond you are going to fill is closed
Fill the first pond
· put the wooden boards in the sluice at the corner of the inlet ditch to the first pond
· take out the wooden boards of the inlet sluice to the first pond and put in the screen
· put the screen in the sluice at the top of the supply ditch and take out the wooden boards one at a time until water begins to flow down the ditch and into the first pond.
76. If you are going to fill another pond you should prepare it now, while the first pond is being filled.
77. To prepare the next pond, do the following
· make sure the outlet of the next pond you want to fill is closed
· put the board in the sluice at the corner of the inlet ditch
· take the boards out of the inlet sluice and put in the screen.
78. Watch your first pond carefully. When it is full of water put back the boards in the inlet sluice and take out the boards in the sluice at the comer of the inlet ditch (see Item 75 in this booklet).
79. The water will now flow further down the supply ditch and begin to fill the next pond.
80. Continue to do this until all of the ponds are full.
81. When your ponds are full of water, put a few of the wooden boards back in the sluice at the top of your supply ditch. However, make sure that some water is always running Into each of your ponds so that they will always be full.
Ponds are filled one by one
· The first pond
1 close outlet
2 close sluice at corner of inlet ditch
3 open inlet sluice
4 open sluice at stream one board at a time
· The first pond will begin to
· Prepare the second pond
5 close outlet
6 close sluice at corner of inlet ditch
7 open inlet sluice
· When the first pond is full
close the inlet sluice (3) and open the sluice at corner of inlet ditch
· The second pond will begin to fill
· Continue to do this until all ponds are full
Make sure that some water is always running down the supply ditch and Into each of your ponds so that they will always be full.