Socio-Economic Trend

Large Dams

UNIT: Thousand dams

Tens of thousands of large dams built over the last two centuries have changed natural river flows and contributed to altering the global water cycle. Dams starve deltas of sediment. As a result, along with mining, irrigation and fossil fuel extraction, many of the world’s deltas are sinking four times faster than sea level is rising.

Graph Caption: Global total number of existing large dams (minimum 15 m height above foundation) based on the ICOLD (International Committee on Large Dams) database.
Source: ICOLD database register search. Purchased 2011.

Caption: Three Gorges Dam, Yangtze River, China
Source: Google Earth
Map Caption: Global distribution of dams
Map Credit: Félix Pharand-Deschênes,
Source: Global Reservoir and Dam v1 (GRanD),