ABSTRACT
While more than three-quarters of the Earth's surface is covered by water, only a tiny fraction is fresh water suitable for use by humans and by most of the plants and animals on which human survival depends (Gleick et al, 2006). While it is one of the most essential resources for human survival, the quantity of fresh water on the planet essentially is fixed or declining. Human activity easily pollutes water, rendering it unfit for human use, while desalination remains an expensive alternative, probably too expensive for use on a mass scale (California Coastal Commission, 2003; Uche, 2003; Symposium, 2006). Moreover, fresh water all too often is available at the wrong time, in the wrong place, or in the wrong amounts: seasonal rains or snows often have run off or been consumed before the end of the growing season, while rain or snow usually falls most heavily on mountains, where the rugged terrain discourages agriculture, rather than on the easily farmed plains. Floods can be followed by drought. All of this has created the felt necessity to manage and control the development and use of water through elaborate engineering schemes and highly centralized political arrangements (Wittfogel, 1957; Teclaff, 1967; Downing and Gibson, 1975).
