Water Budgets for Aquaculture Ponds Supplied by Runoff, with Reference to Effluent Volume

Abstract

Water budgets of four watershed ponds near Auburn in east-central Alabama were measured over a 2-year period. On an annual basis, direct precipitation into three ponds was less than the loss of water in evaporation and seepage, and overflow from ponds averaged 60 to 90% of runoff entering ponds. During the drier part of the year (June to November), there was little overflow, and water levels declined. From December to May, water flowed from ponds following periods of precipitation. The other pond received continual inflow from a spring that exceeded the volume of evaporation and seepage out. On an annual basis, this pond had about 1.4 times as much overflow as entering runoff. The average volume of effluents (overflow) from ponds was 2.5 times pond volume during the 12-month period with above normal rainfall and 1.4 times pond volume during the 12-month period with approximately normal rainfall. Annual overflow from watershed ponds is roughly equal to annual runoff entering ponds; runoff entering ponds may be estimated by subtracting annual evapotranspiration from annual rainfall.