Water Supply (Sep 2021)
Estimation of ecosystem evapotranspiration in a Robinia pseudoacacia L. plantation with the use of the eddy covariance technique and modeling approaches
Abstract
Τhe eddy covariance technique provides reliable ecosystem-level evapotranspiration (ET) measurements. These measurements, when combined with models and satellite products, could offer high spatiotemporal coverage and valuable mechanistic interpretation of the underlying processes. This study address one-year eddy covariance measurements from a Robinia pseudoacacia site in Northern Greece and remote sensing products: we (a) provide a medium-term description of daily ET fluxes for a R. pseudoacacia plantation in a degraded land, (b) assess the contribution of environmental drivers (e.g. net radiation, temperature etc.) on ET and (c) evaluate a simple satellite and meteorological driven model for larger-scale applications, based on the Land Surface Water Index (LSWI) and the FAO approach. R. pseudoacacia was found to have quite high water consumption, especially during leaf expansion. Net radiation and soil water content had the greatest effect on ecosystem evapotranspiration. LSWI was found to be correlated with both soil water content and evapotranspiration. Its use as an index for water limitation in models leads to high accuracy when compared to ET measurements. Our results (a) provide a significant contribution to the assessment of R. pseudoacacia ecophysiology and (b) highlight the potential of accurate ecosystem ET estimation with simple modeling approaches. HIGHLIGHTS The eddy covariance method contributes to the better knowledge of the species ecophysiology, as well as its performance under highly degraded soils.; An evapotranspiration model, evaluated against the eddy covariance measurements, appears to give a very good performance.; Land Surface Water Index was found to correlate well with ecosystem evapotranspiration and can be used as a crop coefficient scalar.;
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