Pond Water Impacts Evaluation

As of 12/13/2019

Water Surface is 0.5 acres or approximately 21,800 SF

  • 21,800 SF at an average 3.5 foot depth = 648,500 gallons.
  • 21,800 x 0.08 = 1,744 CF or 14,800 gallons per inch of depth

Rough rainfall runoff area = 4.7 ac

A 1″ rain over 4.7 ac would be 139k gallons total. If only half runs to the pond then 69,500 gallons would add to the pond 69500/14800 or 4.7 inches.

Evaporation Rates

Below is from Table 1 at https://semspub.epa.gov/work/01/554363.pdf

Fairhope
May-Oct Total = 32.74″. Highest month is June at 6.43″*
Nov-April Total = 17.43″. Highest month is April at 5.03″

All of the evaporation values in these tables represent estimates of expected evaporation occurring from a Class A pan. * It has been found that evaporation from a shallow lake, wet soil, or other moist natural surfaces is roughly 70 percent of the evaporation from a Class A pan for the same meteorological conditions. The evaporation from shallow lakes and moist soils is generally classified by one of the following equivalent names: free water surface evaporation (FWS), lake evaporation (E1 ), or potential evapotranspiration (PE). An estimate of FWS which is more accurate than that given by multiplying the pan value by 0.70, is obtained by multiplying the pan amount by the appropriate coefficient from map 4 of the evaporation atlas described earlier.

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