1 Department of Civil and Environmental Engineering, UC Berkele, Berkeley, California 94720 USA.
2 Soil, Water and Environmental Sciences, A.R.O. - Volcani Center, Bet Dagan, 50250 Israel.
3 Division of Hydrologic Sciences, Desert Research Center, Las Vegas, NV 89119 USA.
4 Nicholas School of the Environment, Duke University, Box 90328, Durham, North Carolina 27708 USA.
5 Geography and Environmental Development, Ben-Gurion University of the Negev, Beer Sheva, Israel.
6 Nicholas School of the Environment, Duke University, Box 90328, Durham, North Carolina 27708 USA ; Pratt School of Engineering, Duke University, Durham, North Carolina 27708 USA.