While historically, experts have concentrated on transboundary surface water, more recently, nations have started to include transboundary groundwater on their agendas as more and more people are depending on groundwater to meet their daily needs.
There are more than 263 internationally shared basins worldwide.
Over 45% of the land surface of the world is covered by basins that are shared by more than one nation. Over 75% of all nations, 145 of them have within their boundaries shared basins. And 33 nations have over 95% of their territory within international basins.
While most basins are shared between just two countries, there are many basins where this number is much higher. There are 13 basins worldwide that are shared between 5 and 8 riparian nations. Five basins, the Congo, Niger, Nile, Rhine and Zambezi, are shared between 9 and 11 countries. The river that flows through the most nations is the Danube, which travels within the territory of 18 nations!
Over 40% of the world’s population resides within internationally shared river basins.
Basins shared by two or more nations account for approximately 60% of the world’s river flow.
Source: UNESCO Water Portal, August 2007