The precarious nature of the relationship between ecosystems, hydrology and human well-being is evidenced, for example, by the collapses of the early ‘great river civilizations’ of the Tigris-Euphrates, the Nile, the Indus-Gangesand the Yellow River (Ito, 1997) that were initiated by hydrological changes and reductions in rainfall of up to 30% in a tract of the globe extending from Europe to the Indus River (Cullen et al., In some cases, desertification initiated by hydro-meteorological changes may have been accelerated by changes in land use, including overgrazing by livestock, as migratory populations sought more favourable agricultural conditions (Weiss et al., A similar history can be traced back to the Maya Civilization (250-950 AD) of Central America (Peterson and Haug, 2005).