Pond filling
The yearly amount of water for filling the ponds is computed on the basis of the following assumptions:
Brood fish and donor ponds are filled once a year.
The total number of fillings for the nursery and rearing ponds is 28.
Thus the average number of fillings for one pond is:
for nursery ponds, and
for rearing ponds
| Pond | No. | Water depth m | Average area ha | Total volume m3 | Number of fillings | Total demand m3 |
| Brood fish pond | 4 | 1.7 | 0.12 | 8 000 | 1 | 8 000 |
| Nursery pond | 51 | 1.0 | 0.10 | 5 000 | 5.6 | 28 000 |
| Rearing pond | 8 | 1.5 | 0.40 | 48 000 | 3.5 | 168 000 |
| Donor pond | 3 | 1.7 | 0.30 | 15 000 | 1 | 15 000 |
| Total | 21 | 219 000 |
Replacement of evaporation losses
The ponds operate during different periods throughout the year and evaporation losses are computed as follows:
| Brood fish ponds | January – December | Evaporation = 3 913 mm |
| Nursery ponds | February – August | Eavporation = 2 712 mm |
| Rearing ponds | March – October | Evaporation = 3 188 mm |
| Donor ponds | January – December | Evaporation = 3 913 mm |
| Brood fish pond | 3 913 mm × 0.48 ha = | 18 800 m3 | (rounded) |
| Nursery pond | 2 712 mm × 0.60 ha = | 16 300 m3 | (rounded) |
| Rearing pond | 3 188 mm × 3.20 ha = | 102 000 m3 | (rounded) |
| Donor pond | 3 913 mm × 0.90 ha = | 35 200 m3 | (rounded) |
| Total evaporation loss | 172 300 m3 |
Replacement of seepage losses
In the absence of soil tests the seepage is estimated to be 20 mm/day. The length of operation period is also taken into account.
| Brood fish pond | 20 mm/day × 365 days × 0.48 ha = | 35 000 m3 | (rounded) |
| Nursery pond | 20 mm/day × 28 weeks × 0.60 ha = | 23 500 m3 | (rounded) |
| Rearing pond | 20 mm/day × 34 weeks × 3.20 ha = | 152 300 m3 | (rounded) |
| Donor pond | 20 mm/day × 365 days × 0.90 ha = | 65 700 m3 | |
| Total seepage loss | 276 500 m3 |
Inflow due to rainfall
The water source for pond filling is the main canal. Therefore the amount of rain is only considered on the pond surface.
| Brood fish pond | 162 mm × 0.48 ha = | 800 m3 | (rounded) |
| Nursery pond | 126 mm × 0.60 ha = | 800 m3 | (rounded) |
| Rearing pond | 135 mm × 3.20 ha = | 4 300 m3 | (rounded) |
| Donor pond | 162 mm × 0.90 ha = | 1 500 m3 | (rounded) |
| Total inflow from rainfall | 7 400 m3 | ||
Summary
The annual water demand is the sum of the above amounts with the appropriate sign.
| Pond filling | + 219 000 m3 |
| Evaporation loss | + 172 300 m3 |
| Seepage loss | + 276 500 m3 |
| Rainfall | - 7 400 m3 |
| Annual water demand | + 675 200 m3 |
| (Rounded to) | 675 000 m3 |
