ABSTRACT
As human populations and economies grow, the amount of freshwater in the world remains roughly the same as it has always been. The total quantity of water in the world is immense, but most is either saltwater (97.5 percent) or locked in ice caps (1.75 percent). The hydrological system pumps over 44,000 cubic kilometers of water onto lands each year, putting the amount available per person at over 6,500 cubic meters per year. However, the amount economically available for human use is only about 13,500 cubic kilometers (0.007 percent of the total on Earth), reducing the amount available to just over 2,300 cubic meters per person per year – a 37 percent drop since 1970.1 This increasing water scarcity is made more complex because almost half of the globe’s land surface lies within international watersheds – a landscape that contributes to the world’s over 276 transboundary waterways. The political boundaries are further complicated by both water quantity and water quality degradation, and rapidly growing rural and urban populations in developing countries. The world is now struggling to respond to the hard facts:
More than one billion people lack access to safe water supplies.
Almost three billion do not have access to adequate sanitation.
Three to five million people die each year from water-related diseases or inadequate sanitation.
20 percent of the world’s irrigated lands are salt laden, degrading crop productivity.2
