1. Institute of Soil, Water and Environmental Sciences, The Volcani Center, Agricultural Research Organization, P.O.B 6, Bet-Dagan, Israel, 50250, Research Department, Israel Hydrological Service, P.O.B. 20365, Tel Aviv 61203, Israel, and The Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boker Campus 84990, Israel