Evaluation of the METRIC and TSEB remote sensing evapotranspiration models in the floodplain area of the Thaya and Morava Rivers

• Published in: Journal of hydrology. Regional studies 2024-06, Vol.53, p.101785, Article 101785
• Main Authors: Ghisi, T., Fischer, M., Nieto, H., Kowalska, N., Jocher, G., Homolová, L., Burchard-Levine, V., Žalud, Z., Trnka, M.
• Format: Article
• Language: English
• Subjects: Eddy covariance; Evapotranspiration; Floodplain ecosystem; Remote sensing models; Water balance
• ISSN: 2214-5818; 2214-5818
• DOI: 10.1016/j.ejrh.2024.101785

Floodplain ecosystem region at the confluence of the Morava and Thaya Rivers, the Czech Republic. Accurate determination of actual evapotranspiration (ETa) is essential for understanding surface hydrological conditions. The aim of this study was to evaluate two remote sensing models, METRIC and TSEB, for estimating ETa and energy fluxes in two ecosystems using the eddy covariance (EC) as a reference. Both models demonstrate the ability to quantify ETa across the region. Compared with the METRIC, which had a mean bias error (MBE) = 0.12 mm/day, the TSEB better detected ETa in the forest test site (MBETSEB = −0.03 mm/day). In contrast, the METRIC improved detection of ETa (MBEMETRIC = −0.03 mm/day) in grassland test site, where the TSEB overestimate daily ETa (MBETSEB = 0.52 mm/day). The models and EC indicate similar seasonal dynamics of the evaporative fraction and Bowen ratio throughout the growing season. Despite the overall agreement between the models and EC, selected spatial outputs indicate some disagreement among them in terms of the spatial patterns of ETa. This disagreement is related to the sensitivity of TSEB to canopy height/roughness, as well as the a priori Priestley–Taylor coefficient in forests. Despite these shortcomings, this study highlights the applicability of remote sensing energy balance-based diagnostic models for studying hydrological processes in a spatially distributed manner. [Display omitted] •The METRIC and TSEB models are evaluated at two test sites using eddy covariance in a floodplain ecosystem.•The results show good agreement between both models and the eddy covariance data.•Averaging the models' results demonstrates improved agreement with the eddy covariance compared to those of single models.•Models and eddy covariance indicate a temporal variation of the evaporative fraction and Bowen ratio during growing season.•Spatial outputs indicate disagreement among the models, indicating the sensitivity of TSEB to the landcover-specific PT coefficient.