Comparison of selected methods predicting reference crop evapotranspiration in Thailand
- Bangkok : Asian Institute of Technology, 1986
- 97 p.
- Thesis ; no. WA-86-20 .
- Asian Institute of Technology. Thesis ; no. WA-86-20 .
A thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering, School of Engineering and Technology
Thesis (M.Eng.) - Asian Institute of Technology, 1986
This study Ras undertaken to find out which methods predicting reference crop evapotranspiration ETo (four methods suggested by FAO and the Jensen- Raise method) should be preferred for a region with a specific climate based on monthly data for a 10-year period (1974 - 1983). The methods were compared against ETo estimated by the Penman method as this method has been found by many studies to be reliable and the best estimation method for ETo. Thailand has been divided into 5 regions based on the characteristic of the estimated ETo-values by the Penman method and the climatic variables during the dry and wet seasons, based on data of 20 agrometeorological observation stations. The general trend of ETo estimated by the Pan Evaporation and Jensen Haise method is the best in the dry season, the Radiation and Jensen Raise methods give the best in the wet season for all regions. The Radiation and Jensen- Heise method give a good correlation with the Penman method. The Radiation method gives the closest estimation of ETo for all regions during dry and wet seasons.