1. Department of Agroecology, Faculty of Science and Technology; Aarhus University; Blichers Allé 20, PO Box 50 DK-8830 Tjele Denmark
2. Department of Civil Engineering; Aalborg University; Sohngaardsholmsvej 57 DK-9000 Aalborg Denmark
3. Department of Water Engineering, Faculty of Agriculture; Shiraz University; Shiraz Iran
4. Department of Soil, Water and Environmental Science; The University of Arizona; Tucson AZ 85721 USA