Now, for the first time, a high-resolution map shows where underground aquifers store vast amounts of water.
[...The map project] has identified 273 trans-boundary aquifers: 68 in the Americas, 38 in Africa, 155 in Eastern and Western Europe and 12 in Asia.
Each trans-boundary aquifer holds the potential for international conflict – if two countries share an aquifer, pumping in one country will affect its neighbour's water supply.
In many parts of the world, around the Mediterranean for example, but also in the US and the Middle East, water tables are falling and aquifers are being infiltrated by seawater as agricultural practices pump water out faster than it can be replenished by rain.
When aquifers fall between countries, sustainable management requires international agreement. Yet, historically, many agreements have been weighted towards the richest or more powerful country.
Deeplink to map Groundwater resources of the world (4½ MB PDF).