A simple model to estimate monthly forest evapotranspiration in Japan from monthly temperature

Hikaru Komatsu, Tomonori Kume, Kyoichi Otsuki

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10 Citations (Scopus)


The estimation of evapotranspiration (E) in forested areas is required for various practical purposes (e.g. evaluation of drought risks) in Japan. This study developed a model that estimates monthly forest E in Japan with the input of monthly temperature (T). The model is based on the assumptions that E equals the equilibrium evaporation rate (Eeq) and that Eeq is approximated by a function of T. The model formulates E as E (mm month-1) = 3.48 T (°C) + 32.3. The accuracy of the model was examined using monthly E data derived using short-term water balance (WB) and micrometeorological (M) methods for 15 forest sites in Japan. The model estimated monthly E more accurately than did the Thornthwaite and Hamon equations according to regression analysis of the estimated E and E derived using the WB and M methods. Although the model tended to overestimate monthly E, the overestimation could be reduced by considering the effect of precipitation on E. As T data are commonly available all over Japan, the model would be a useful tool to estimate forest E in Japan.

Original languageEnglish
Pages (from-to)1896-1911
Number of pages16
JournalHydrological Processes
Issue number13
Publication statusPublished - Jun 1 2010

All Science Journal Classification (ASJC) codes

  • Water Science and Technology


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