1 / 31

STEP BY STEP CALCULATION DAILY EVAPOTRANSPIRATION ( ETo ) EXAMPLE

STEP BY STEP CALCULATION DAILY EVAPOTRANSPIRATION ( ETo ) EXAMPLE. PENMAN-MONTEITH METHOD FAO PAPER NO. 56 Komariah , PhD. Given Information. Date : July 6, 2011 Location: UNS : 7 o 33’ S Elevation: 100 m asl T max : 21.5 o C T min : 12.3 o C. RH max: 84% RH min: 63%

phoebe
Download Presentation

STEP BY STEP CALCULATION DAILY EVAPOTRANSPIRATION ( ETo ) EXAMPLE

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. STEP BY STEP CALCULATIONDAILY EVAPOTRANSPIRATION (ETo)EXAMPLE PENMAN-MONTEITH METHOD FAO PAPER NO. 56 Komariah, PhD.

  2. Given Information • Date : July 6, 2011 • Location: UNS : 7o33’ S • Elevation: 100 m asl • T max : 21.5 oC • T min : 12.3oC • RH max: 84% • RH min: 63% • Wind speed at 10 m : 10 km/h  2.78 m/s • Sunshine: 9.25 hours Q: Determine Eto ???

  3. EQUATION

  4. Step : 1 • Determine T as T mean: T = (T max + T min )/ 2 T = (21.5 + 12.3)oC / 2 = 16.9 oC

  5. Step 2 : • Determine 

  6. Or, use Table 2.2

  7. Step: 3 • Determine ∆

  8. Or, use Table 2.4 • Interpolation  ∆ = 0.122 kPa/oC

  9. Step 4: • Determine u2 from

  10. Or, use Table 2.9 • u2 = 2.78 x 0.748 = 2.078 m/s

  11. Step 5: • Determine es from

  12. Or, use Table 2.3 • es = (2.564 + 1.431) /2 = 1.997 kPa

  13. Step 5: • Determine ea from •  ea = 1.409 kPa

  14. Step 6: • Determine G from

  15. Step 7: • Determine Rn from

  16. Step 7-1:

  17. Step 7-1-1: Recommendation: a= 0.25 and b= 0.50

  18. Step 7-1-1-1: Or, Use Table 2.6

  19. Interpolation, Ra = 30.9 MJ m-2 d-1

  20. Step 7-1-1-2: Or, Use Table 2.7

  21. Interpolation, N = 11.63 hours

  22. …Back to Step 7-1-1: Recommendation: a= 0.25 and b= 0.50 Calculate, Rs = 20.01 MJ m-2 d-1

  23. … Back to Step 7-1: Calculate, Rns = 15.41 MJ m-2 d-1

  24. Step 7-2: Step 7-2-1: Use Table 2.8

  25. T min : 12.3; Interpolate   = 32.56 MJ/m2 d T max : 21.5;   = 36.96 MJ/m2 d Calculate = 34.76 MJ m-2 d-1

  26. Step 7-2-2: Calculate, Rso = 23.24 MJ m-2 d-1

  27. … Back to Step 7-2: CalculateRnl = 4.91 MJ m-2 d-1

  28. … Back to Step 7: • Determine Rn from CalculateRn = 10.50 MJ m-2 d-1

  29. Step 8 (FINAL): CalculateETo = 3.29 mm d-1

  30. Crop Evapotranspiration (ETc)  Crop Water Requirement

  31. ETc = Kc x ETo

More Related