Transboundary waters

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Transboundary waters account for 60% of the Earth’s freshwater flows.

A watershed is an area of land that drains water into a body of water, such as a river, lake, or ocean; therefore, they are geographic regions defined by the natural boundaries of water flow. There are 276 transboundary watersheds in the world:

  • 68 in Europe
  • 64 in Africa
  • 60 in Asia
  • 46 in North America
  • 38 in South America
Internacional river basing

International River Basins

In addition:

  • 153 countries (and areas) share transboundary waters
  • 200 transboundary aquifers are recorded
  • There are 592 transboundary aquifer systems
  • 40% of the world’s population lives in these basins

In addition:

  • The 263 transboundary lakes and river basins constitute almost half of the Earth’s surface.
  • 21 countries are located entirely within international basins.
  • 39 countries share more than 90% of their territory with one or more other countries through transboundary rivers.
Transboundary Hydrological basins

Transboundary Hydrological basins

  • While most of the basins are shared by two countries, in many others the number is much higher. There are 13 basins worldwide shared between 5 and 8 nations.
  • Five other basins, involving the Congo, Niger, Nile, Rhine and Zambezi rivers, are shared between 9 and 11 countries.
  • The river that crosses the largest number of countries is the Danube, which flows through the territory of 18 nations.
  • 58% of the world’s transboundary basins are subject to operational arrangements for water cooperation (indicator 6.5.2 of the Sustainable Development Goals, SDGs, 2020).
  • More than 3 600 agreements and treaties related to transboundary waters have been signed.


PNUD, Programa de las Naciones Unidas para el Desarrollo. (2006). Capítulo 6. En: Informe sobre Desarrollo Humano 2006. Más allá de la escasez: poder, pobreza y crisis mundial del agua. Recuperado de
Red del Agua UNAM. (25 nov 2019). Aguas transfronterizas. Recuperado de
UN Water. (s.f.). Transboundary waters. Recuperado de y

Transboundary waters