Testing the water balance model CRITERIA using TDR measurements, micrometeorological data and satellite-based information.

Aiming at developing real time water balance modelling for irrigation scheduling, this study assesses the accuracy of the soil water balance model CRITERIA, developed by the hydro-meteorological service of the Emilia-Romagna region (Italy). The model consists of (i) an algorithm for coupling the surface flow components (i.e. Richards equation), and (ii) various modules which may be applicable to different topographical and environmental conditions. In this study, CRITERIA was applied to simulate the soil water balance for an orange orchard in semi-arid Mediterranean conditions (Eastern Sicily, insular Italy) during the cropping season 2011. The model was implemented by varying the evapotranspiration rates (ET) as input; ET fluxes were estimated by using satellite-based approach and the Penman-Monteith expression for reference rates, or were directly measured by the eddy covariance technique and the sap flow heat pulse method for transpiration. Model outputs, in term of soil moisture, were validated with direct measures of volumetric soil water content obtained by time domain reflectrometry (TDR) probes. Results of the study proved the reliability of CRITERIA to reproduce the soil moisture profile at the experimental site. The model performance was significantly high when direct measurements of crop water demand were included as input for model application. The satellite-based approach provided reliable crop evapotranspiration estimates, confirming the utility of the remote sensing techniques as support for water management in agriculture.