Insights into evapotranspiration partitioning based on hydrological observations using the generalized proportionality hypothesis.
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| Title: | Insights into evapotranspiration partitioning based on hydrological observations using the generalized proportionality hypothesis. |
|---|---|
| Authors: | Hassan, Amin1 (AUTHOR), Prentice, Iain Colin2,3 (AUTHOR), Liang, Xu1 (AUTHOR) xuliang@pitt.edu |
| Source: | Hydrology & Earth System Sciences. 2026, Vol. 30 Issue 2, p317-341. 25p. |
| Subject Terms: | *Evapotranspiration, *Plant transpiration, *Plant communities, *Hydrology, *Watersheds, *Water balance (Hydrology), *Leaf area index, *Arid regions |
| Geographic Terms: | United States |
| Abstract: | Evapotranspiration comprises transpiration, soil evaporation, and interception. The partitioning of evapotranspiration is challenging due to the lack of direct measurements and uncertainty of existing evapotranspiration partitioning methods. We propose a novel method to estimate long-term mean transpiration to evapotranspiration (Et/E) ratios based on the generalized proportionality hypothesis using long-term mean hydrological observations at the watershed scale. We tested the method using 648 watersheds in the United States classified into six vegetation types. We mitigated impacts of the variability associated with different Ep data products by rescaling their original Ep values using the product E/Ep ratios in combination with the observed E calculated from watershed water balance. With Ep thus rescaled, our method produced consistent Et/E across six widely used Ep products. Shrubs (0.33) and grasslands (0.32) showed lower mean Et/E than croplands (0.48) and forests (respectively 0.69, 0.60, and 0.70 for evergreen needleleaf, deciduous broadleaf, and mixed forests). Et/E showed significant dependence on aridity, leaf area index, and other hydrological and environmental conditions. Using Et/E estimates, we calculated transpiration to precipitation ratios (Et/P) ratios and revealed a bell-shaped curve at the watershed scale, which conformed to the bell-shaped relationship with the aridity index (AI) observed at the field and remote-sensing scales (Good et al., 2017). This relationship peaked at an Et/P between 0.5 and 0.6, corresponding to an AI between 2 and 3 depending on the Ep dataset used. These results strengthen our understanding of the interactions between plants and water and provide a new perspective on a long-standing challenge for hydrology and ecosystem science. [ABSTRACT FROM AUTHOR] |
| Database: | Energy & Power Source |
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| Header | DbId: enr DbLabel: Energy & Power Source An: 191384993 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Insights into evapotranspiration partitioning based on hydrological observations using the generalized proportionality hypothesis. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Hassan%2C+Amin%22">Hassan, Amin</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Prentice%2C+Iain Colin%22">Prentice, Iain Colin</searchLink><relatesTo>2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Liang%2C+Xu%22">Liang, Xu</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> xuliang@pitt.edu</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Hydrology+%26+Earth+System+Sciences%22">Hydrology & Earth System Sciences</searchLink>. 2026, Vol. 30 Issue 2, p317-341. 25p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22Evapotranspiration%22">Evapotranspiration</searchLink><br />*<searchLink fieldCode="DE" term="%22Plant+transpiration%22">Plant transpiration</searchLink><br />*<searchLink fieldCode="DE" term="%22Plant+communities%22">Plant communities</searchLink><br />*<searchLink fieldCode="DE" term="%22Hydrology%22">Hydrology</searchLink><br />*<searchLink fieldCode="DE" term="%22Watersheds%22">Watersheds</searchLink><br />*<searchLink fieldCode="DE" term="%22Water+balance+%28Hydrology%29%22">Water balance (Hydrology)</searchLink><br />*<searchLink fieldCode="DE" term="%22Leaf+area+index%22">Leaf area index</searchLink><br />*<searchLink fieldCode="DE" term="%22Arid+regions%22">Arid regions</searchLink> – Name: SubjectGeographic Label: Geographic Terms Group: Su Data: <searchLink fieldCode="DE" term="%22United+States%22">United States</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Evapotranspiration comprises transpiration, soil evaporation, and interception. The partitioning of evapotranspiration is challenging due to the lack of direct measurements and uncertainty of existing evapotranspiration partitioning methods. We propose a novel method to estimate long-term mean transpiration to evapotranspiration (Et/E) ratios based on the generalized proportionality hypothesis using long-term mean hydrological observations at the watershed scale. We tested the method using 648 watersheds in the United States classified into six vegetation types. We mitigated impacts of the variability associated with different Ep data products by rescaling their original Ep values using the product E/Ep ratios in combination with the observed E calculated from watershed water balance. With Ep thus rescaled, our method produced consistent Et/E across six widely used Ep products. Shrubs (0.33) and grasslands (0.32) showed lower mean Et/E than croplands (0.48) and forests (respectively 0.69, 0.60, and 0.70 for evergreen needleleaf, deciduous broadleaf, and mixed forests). Et/E showed significant dependence on aridity, leaf area index, and other hydrological and environmental conditions. Using Et/E estimates, we calculated transpiration to precipitation ratios (Et/P) ratios and revealed a bell-shaped curve at the watershed scale, which conformed to the bell-shaped relationship with the aridity index (AI) observed at the field and remote-sensing scales (Good et al., 2017). This relationship peaked at an Et/P between 0.5 and 0.6, corresponding to an AI between 2 and 3 depending on the Ep dataset used. These results strengthen our understanding of the interactions between plants and water and provide a new perspective on a long-standing challenge for hydrology and ecosystem science. [ABSTRACT FROM AUTHOR] |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.5194/hess-30-317-2026 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 25 StartPage: 317 Subjects: – SubjectFull: Evapotranspiration Type: general – SubjectFull: Plant transpiration Type: general – SubjectFull: Plant communities Type: general – SubjectFull: Hydrology Type: general – SubjectFull: Watersheds Type: general – SubjectFull: Water balance (Hydrology) Type: general – SubjectFull: Leaf area index Type: general – SubjectFull: Arid regions Type: general – SubjectFull: United States Type: general Titles: – TitleFull: Insights into evapotranspiration partitioning based on hydrological observations using the generalized proportionality hypothesis. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Hassan, Amin – PersonEntity: Name: NameFull: Prentice, Iain Colin – PersonEntity: Name: NameFull: Liang, Xu IsPartOfRelationships: – BibEntity: Dates: – D: 15 M: 01 Text: 2026 Type: published Y: 2026 Identifiers: – Type: issn-print Value: 10275606 Numbering: – Type: volume Value: 30 – Type: issue Value: 2 Titles: – TitleFull: Hydrology & Earth System Sciences Type: main |
| ResultId | 1 |
