1. Department of Natural Resources, Faculty of Geo-Information Science and Earth Observation (ITC-NRS) University of Twente ; Hengelosestraat 99, 7514 AE Enschede , The Netherlands ; mariajo_gb@hotmail.com
2. Department of Irrigation, Centro de Edafología y Biología Aplicada del Segura (CEBAS-CSIC) P.O. Box 164, E-30100 Espinardo, Murcia , Spain
3. Department of Agriculture, Food and Environment (DAFE) ; University of Pisa Via del Borghetto 80-56124 , Pisa , Italy