Estimation of Evapotranspiration ill a Rice Irrigation Scheme in Peninsular Malaysia
The correct estimation of ET in the water balance equation allows for improved water management in rice cultivation. Eight evapotranspiration estimation methods (Penman, Penman-Monteith, Pan Evaporation, Kimberly-Penman, Priestley-Taylor, Hargreaves, Samani-Hargreaves and Blaney-Criddle) were tes...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English English |
| Published: |
Universiti Putra Malaysia Press
2005
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| Online Access: | http://psasir.upm.edu.my/id/eprint/3876/1/Pages_from_JST_VOL._13_NO._2-10.pdf http://psasir.upm.edu.my/id/eprint/3876/ |
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| Summary: | The correct estimation of ET in the water balance equation allows for improved
water management in rice cultivation. Eight evapotranspiration estimation
methods (Penman, Penman-Monteith, Pan Evaporation, Kimberly-Penman,
Priestley-Taylor, Hargreaves, Samani-Hargreaves and Blaney-Criddle) were tested
with 30 years of daily data, at a study site in the west coast of Peninsular
Malaysia. The estimation of evapotranspiration by all methods showed the same
trend throughout the year. The Samani-Hargreaves method gave the highest
estimation followed by the Priestley-Taylor and Hargreaves methods. The
Penman-Monteith method gave the lowest estimations of evapotranspiration
followed by the Blaney-Criddle method and then the Pan method. The Penman-Monteith, Blaney-Criddle and Pan methods gave lower values of
evapotranspiration with no significant difference among them (P = 0.05). All
the other estimation methods were significantly different from these three
methods. The Penman method, though was different from the three methods
in terms of development; however, it estimates evapotranspiration close to
these three methods. The Penman-Monteith, Blaney-Criddle and Pan were
found to be the better methods to estimate evapotranspiration in the study
area. Results from this study showed that the Penman method can be used to
get somewhat reasonable estimates though it tends to overestimate
evapotranspiration. Comparisons of these selected methods against the PenmanMonteith
method showed that they have good correlation. The Pan, BlaneyCriddle
and Penman gave correlation coefficients of 0.87, 0.55 and 0.97
respectively. A simple correlation equation, developed using 3D-year daily data,
showed that direct measurement of net radiation can be used to estimate
reference evapotranspiration with considerable accuracy (r2 = 0.97) |
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