The world'stransboundary rivers and aquifers Transboundary river basins Transboundary aquifers* Number area in international Number basins Africa 59 62 40 Asia 57 40 70 Europe 69 55 89 North and Central America 40 37 41 South America 38 59 29 Total (global) 263 48 269 *Data on areas of transboundary aquifers are limited,and only available for selected aquifers. Sources:International river basins from Wolf et al.(1999)and updated in 2002; international aquifers from UNESCO(2009). The world’stransboundary rivers and aquifers Sources: International river basins from Wolf et al. (1999) and updated in 2002; international aquifers from UNESCO (2009)