Testing evapotranspiration retrieval approaches over Hungarian agricultural fields

Evapotranspiration (ET) is a key element of water cycle especially over vegetated surface. Vegetation in Hungary is often prone to drought events, while exact information on water need of different species is barely available.  Vast majority of the agricultural lands are rainfed, without the option of irrigation, hence water balance components are in the focus of research interest in case of different agricultural settings. Moreover, crop growth models of different approaches rely heavily on ET estimations. Water balance components are essential to assess crop health, or estimate future crop growth.

In this work we present calculations of actual evapotranspiration using different methods. Flexibility in parameterization, data requirements and their availability and performance are tested in case of all methods to select the best candidates for Hungarian agricultural applications. We use empirical and process based approaches to evaluate the feasibility of the methods in case of Hungarian conditions. A multiannual analysis ensures that the differences among years are better considered. To ensure that data on other components of water balance are considered, we apply the ET estimation methods to selected stations of the drought monitoring network of General Directorate of Water Management, where continuous soil moisture content data are recorded. Measurement stations are located typically over agricultural fields. Representation of different crop and soil types are ensured in site selection. Weather data for the ET calculations are provided by the homogenized and gridded database of the HungaroMet (Hungarian Meteorological Service). In the future eddy covariance based and lysimeter data will serve as basis for the validation of potential models.