Using MODIS data for monitoring evapotranspiration in vineyards

In North-Eastern Italy water demand for vineyards irrigation is constantly increasing, but this conflicts with the high civil and industrial rates of water consumption in the region, which is one of the most densely populated in Europe. An appropriate management of water resources is therefore mandatory to maximise the efficiency of the whole water supply system. In this context, the fundamental prerequisite is the accurate assessment of the amount and spatio-temporal distribution of vineyard evapotranspiration (ET). This work aims at developing methodologies based on Remote Sensing for mapping water consumption in vineyards at the regional level. MODIS data, which are released at a very high time frequency with a high spectral resolution, appear to be suitable to derive usefuil information about the physiological status of vegetation, including ET. A study-site, consisting in a rather extended vineyard (25 ha) was individuated, and a monitoring eddy flux tower was installed. After having obtained MODIS time-series data for the site, ET was estimated according to a modelling approach based on MODIS data coupled with ground-measured daily meteorological observations. ET estimates were then validated against a four-years dataset of eddy covariance measurements. Two-years time-series of measurements were used for calibrating the models, while the other two were reserved for independent validation. The results obtained showed good consistency with in situ observations, and demonstrate that MODIS data are potentially suitable for monitoring ET in vineyards at the regional scale.