AN [an@hcm.fpt.vn] asked:
>In the message answering Jacky comment about effective water
> volume, you said about evaporation and leakage.
>My question is how to calculate the effective water volume of
>the ponds? Because of evaporation and leakage, were there
>any change of water volume during the time of raising fish?

Dear Friends:

In China, the area of a pond is measured according to the length and the
width of the top of a pond, but the effective water volume depends on
the actual area of the water surface multiplied by the water level
during the culturing period. So the effective water volume is always
smaller than the theoretical volume. Furthermore, the actual area of the
water surface is easily measured whereas it is difficult to measure the
accurate water level if the pond bottom is not even. However, this is
always the case. I don't know how Guquan Village measured the water volume in 1989.

Li Kangmin