Modeling Soil Water Balance and Evapotranspiration in Climate Manipulated Shrubland Ecosystems

Climate change conditions are expected to have significant impacts on soil water balance where evapotranspiration (ET) is the most important component. In the last decades, most studies focused on the development of methods for estimating the actual evapotranspiration (ETa) in agricultural systems (e.g. water demand of crops under climate change). Assessing ETa of natural sparse canopies is challenging, due to the lack of experimental data and difficulties to account for terrain and vegetation variability in natural ecosystems. Moreover, the assessment of ETa over large spatial scale is often time consuming, and requires several measurement points with quite expensive and sophisticated instrumentation and techniques (e.g. eddy covariance). A relatively new modeling approach based on the use of site and vegetation coefficients showed to be a good tool for estimating ETa over natural ecosystems (ECOWAT model, Spano et al., 2009). In the framework of the EU FP7 INCREASE project, ECOWAT was applied to assess the soil water balance of shrubland ecosystems in two experimental sites located in Hungary and Italy. The soil water balance was estimated under current climate conditions and in climate manipulated experimental plots. In addition, an independent set of ETa data were obtained using the Surface Renewal micrometeorological technique to estimate the sensible heat flux values and the energy balance equation to get the latent heat component as residual term. The results showed a good agreement between the two independent datasets, indicating ECOWAT as a promising tool to estimate ETa in natural sparse canopies.