I am looking for the formula to determine the evaporation rate of a body of still water in east Tenessee ?

Question

Am putting in a pond and servicing with a well. Need to determine how much refill will be needed to maintain desired level.

Answer 1

Start with the reference and its references, especially the weather service evaporation map.  Or just do the experiment.  And consider whether evaporation is the only (or main) way for water to leave the pond.  Without an impervious bottom, some will infiltrate the ground.