Aquaculture Engineering

Pond dyke - Partition dyke or secondary dyke

Unit 8 - Brackish and marine water fish farms

Marine water fish farms

Pond dyke

Partition dyke or secondary dyke

Partition dyke or secondary dyke divides the pond system in compartments. Its height is computed by following equation.

H_p = H+ H_w + H_f + H_s

Where,
H_p = Height of partition dyke (m)
H = Maximum desired depth of water in the pond (m)
H_w = Dyke height required for wave action (m)
H_f = Dyke height required for optimum free board
H_s = Dyke height required for settlement

Maximum desired depth of water in coastal aquaculture ponds is usually less than 1.5 m. Dyke height must be sufficient to prevent overtopping due to wave action. Wave height is a function of fetch, which is the unobstructed straight line distance from the furthest point in the pond to dyke. It can be calculated by the following equation.

H_w = Wave height (m)
F = Fetch
The free board requirement in the pond will vary according to site conditions and local requirements. For ponds with secondary dykes up to 200 m long, a minimum free board 0.3 m should be provided. Where as for ponds between 200 m and 400 m long minimum free board should be 0.5 m. Allowance for settlement is usually calculated as a percentage of partition dyke height H. Average settlement allowance used is between 10 and 25 percent of dyke height, minimum allowance being 5%. Top width of secondary dyke is usually between 1 to 2 m.