Effect of vegetation treatment and water stress on evapotranspiration in bioretention systems

Simon De-Ville*, Jill Edmondson, Daniel Green, Ross Stirling, Richard Dawson, Virginia Stovin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
2 Downloads (Pure)


Evapotranspiration is a key hydrological process for reducing stormwater runoff in bioretention systems, regardless of their physical configuration. Understanding the volumes of stormwater that can be returned to the atmosphere via evapotranspiration is, therefore, a key consideration in the design of any bioretention system. This study establishes the evapotranspiration dynamics of three common, structurally different, bioretention vegetation treatments (an Amenity Grass mix, and mono-cultures of Deschampsia cespitosa and Iris sibirica) compared with an un-vegetated control using lab-scale column experiments. Via continuous mass and moisture loss data, observed evapotranspiration rates were compared with those predicted by the FAO-56 Penman–Monteith model for five 14-day dry periods during Spring 2021, Summer 2021, and Spring 2022. Soil moisture reductions over the 14-day trials led to reduced rates of evapotranspiration. This necessitated the use of a soil moisture extraction function alongside a crop coefficient to represent actual evapotranspiration from FAO-56 Penman–Monteith reference evapotranspiration estimates. Crop coefficients (Kc) varied between 0.65 and 2.91, with a value of 1.0 identified as a recommended default value in the absence of treatment-specific empirical data. A continuous hydrological model with Kc=1.0 and a loading ratio of 10:1 showed that evapotranspiration could account for between 1 and 12% of the annual water budget for a bioretention system located in the UK and Ireland, increasing to a maximum of 35% when using the highest Kc observed (2.91).

Original languageEnglish
Article number121182
JournalWater Research
Early online date24 Jan 2024
Publication statusPublished - 15 Mar 2024


  • Bioretention
  • Evapotranspiration
  • Hydrological performance
  • Stormwater management
  • Sustainable Drainage Systems (SuDS)
  • Urban green infrastructure

ASJC Scopus subject areas

  • Environmental Engineering
  • Civil and Structural Engineering
  • Ecological Modelling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution


Dive into the research topics of 'Effect of vegetation treatment and water stress on evapotranspiration in bioretention systems'. Together they form a unique fingerprint.

Cite this