I got a request from one of the Georgia extension agents for some average evapotranspiration data. You might be asked about this too, so I thought I would post the information here.
I found these curves for some Georgia locations from a paper published by Suleiman and Hoogenboom in the Journal of Irrigation and Drainage Engineering. I can get to it via https://www.researchgate.net/publication/245289139_Comparison_of_Priestley-Taylor_and_FAO56_Penman-Monteith_for_Daily_Reference_Evapotranspiration_Estimation_in_Georgia.
For completeness, here is also data on evaporation in Georgia (sorry if the formatting is off):
Pan evaporation data for Georgia stations (in inches)
Source: NOAA Technical Report NWS 34, Mean Monthly, Seasonal, and Annual Pan Evaporation for the United States, Richard K. Farnsworth and Edwin S. Thompson, December 1982
Estimated monthly values for NWS sites
Station J F M A M J J A S O N D Annual
Athens 2.20 2.66 4.16 5.51 6.43 6.64 6.54 6.36 5.06 4.20 2.99 1.17 55.01
Atlanta 2.12 2.73 4.28 5.78 7.03 7.10 7.07 6.70 5.22 4.14 2.89 2.26 57.13
Augusta 2.18 2.75 4.25 5.66 6.27 6.62 6.49 6.31 5.07 4.19 3.00 2.29 55.09
Columbus 2.05 2.66 4.16 5.51 6.76 6.76 6.10 6.16 5.32 4.35 2.77 2.10 54.91
Macon 2.25 2.92 4.64 6.47 7.85 7.67 7.55 7.14 5.83 4.36 3.03 2.45 62.16
Savannah 2.30 2.87 4.76 6.70 7.62 7.51 7.79 6.83 5.67 4.45 3.06 2.60 61.82
Measured monthly values from pan evaporation stations
Station J F M A M J J A S O N D Annual
Ailey 2.09 3.06 4.53 5.46 6.61 6.61 6.64 6.21 4.61 3.74 2.64 2.07 54.27
Allatoona Dam
– 3 3.87 5.06 5.77 6.27 6.55 5.97 4.71 3.46 2.32 – –
Athens College of Agriculture
2.76 3.20 4.82 6.12 7.13 7.49 7.63 6.83 5.65 4.21 3.03 2.53 61.40
Calhoun Experimental Station
– – 4.63 5.75 6.04 7.24 7.25 6.54 5.23 4.22 3.00 3.00 –
Experiment
2.57 3.10 4.78 6.26 7.53 7.96 7.58 6.95 5.61 4.32 3.04 2.36 62.06
Rome 1.77 2.76 3.85 5.29 6.37 6.69 6.85 6.02 5.05 3.76 2.32 1.54 52.27
Savannah 3 3.67 5.69 7.42 7.76 7.91 8.29 7.21 5.75 5.12 3.42 3 68
Tifton Experimental Station
2.22 2.78 4.53 6.00 7.08 6.97 6.81 6.32 5.13 4.24 2.80 2.17 57.05
Note that months with values of only one digit do not have enough historical data to give a more precise amount. Missing data are shown with a ‘-‘.
For the May-October period, the evaporation from a Free Water Surface can be estimated by multiplying the pan evaporation by 0.75.
