Quantifying and partitioning evapotranspiration (ET) into evaporation (E) and transpiration (T) is challenging but important for interpreting vegetation effects on the water balance. We applied a model based on the theory of maximum entropy production (MEP) to estimate ET for shrubs for the first time in a low-energy humid headwater catchment in the Scottish Highlands. In total, 53% of rainfall over the growing season was returned to the atmosphere through ET (59±2% as transpiration), with 22% of rainfall ascribed to interception loss and understory ET. The remainder of rainfall percolated below the rooting zone. The MEP model showed good capability for total ET estimation, in addition to providing a first approximation for distinguishing E and T in such ecosystems. This study shows that this simple and low-cost approach has potential for local to regional ET estimation with availability of high-resolution hydroclimatic data. Limitations of the approach are also discussed.
Bibliographical noteWe would like to thank The Leverhulme Trust (project PLATO, RPG-2014-016) and
the European Research Council (ERC, project GA 335910 VeWa) for funding. We also
thank three anonymous reviewers for their invaluable comments that improved the manuscript substantially. Data in this study can be accessed upon request to the authors.
- water balance
- climate change
- northern uplands
- maximum entropy production