Prospects of Direct Evapotranspiration Measurements for the Immediate Societal benefits

Over the last 30 years, dozens of networks of eddy covariance flux stations have been introduced in different countries and continents around the world. Many of them, such as the ICOS network in Europe or the AmeriFlux network in the US, have a specific focus on greenhouse gas measurement focus, mainly CO_2, but in all cases, the latent heat flux is concurrently measured as a required variable, thus actual evapotranspiration can be derived.

This important hydrologic parameter is needed both in rainfed and irrigated areas to monitor drought conditions, and soil water balance as well as to determine irrigation water amounts to be applied to crops and the timing of optimal fertilizer applications. Quasi-real-time measurements of actual evapotranspiration can be used by water managers, crop consultants, and producers in both rainfed and irrigated agriculture, reducing water and energy use and associated expenses, ultimately helping increase the efficiency of global food production while reducing its costs. So, the importance of providing freely available, scientific-grade data is imperative.

The cutting-edge technologies to assess water use on leaf-level to ecosystem-level scales has been actively developed in academia for past 40 years. One example of such technologies is a next-generation fully-automated evapotranspiration station network, to effectively and efficiently handle the “big data” on water use coming from a grid of measurement stations providing high spatial and temporal coverage of water usage on multiple scales, ranging from a single watershed to a region, state, or a continent.

This presentation aims to provide multiple examples, and validations against existing standards, of the latest technology, hardware, and scientific method behind the eddy covariance approach to direct, field-scale, unattended, and automated measurements of evapotranspiration.