Comment on “A hybrid approach combining the FAO-56 method and the complementary principle for predicting daily evapotranspiration on a rainfed crop field’ by D. Kim et al.

Research output: Contribution to journalComment/debate


Kim et al. (2019) proposed to scale the generalized complementary-relationship-obtained daily evapotranspiration (ETGCR) rate by the wet-environment ET value (ETw) as an index (Ks) of soil water stress but they did not tie their index-values to any soil moisture data. With daily measurements from the same study area (Mead, Nebraska) and period (2002–2012) it is demonstrated that there indeed exists a statistically significant near-linear relationship between Ks (=ETGCR/ETw) and the volumetric soil water content (VWC) when scaled by its maximum observed value, a proxy for field capacity (FC). The soil moisture data therefore support, with increasing reliability as the length of the averaging period grows, the employment of ETGCR/ETw as a practical indicator of soil water stress, the latter here defined as VWC/FC.

Original languageEnglish
Article number124031
JournalJournal of Hydrology
Publication statusPublished - Nov 2019



  • Complementary relationship of evaporation
  • Crop evapotransiration
  • FAO method
  • Soil water stress

ASJC Scopus subject areas

  • Water Science and Technology

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