Rainfall supply projections 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.
All of the evaporation values in these tables represent estimates of expected evaporation occurring from a Class A pan …. 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. [See analysis below.]
|Our Pond Volume at 160,000 gallons/ft = 13,300 gallons/inch|
|From NWS 33 – Annual Class A Pan Avg. of 15 years Evaporation in Fairhope AL From Table 2, inches||51|
|NWS 33 Map 4 coefficient for May-Oct||0.76|
|Monthly Percent of Annual Evaporation from NWS 33 Table 2 (1)||Projected Evaporation Inches/Month||76% adj for shallow ponds||Gallons Evaporated from Our Pond||Pump hours per month at 20 GPM to Offset Evaporation w/o Rain|
(1) Class A Pan, Station in Fairhope 2NE, AL.