Humans have manipulated rivers for thousands of years, but over the last 200 years dams on rivers have become rampant. Reservoirs and dams are constructed for water storage, to reduce the risk of river flooding, and for the generation of power. They are one of the major footprints of humans on Earth and change the world's hydrological cycle.
This dataset illustrates the construction of dams worldwide from 1800 to the present. We display all dams listed in the Global Reservoir and Dam Database (GRanD). It includes 6,862 records of reservoirs and their associated dams. All dams that have a reservoir with a storage capacity of more than 0.1 cubic kilometers are included, and many smaller dams were added where data were available. The total amount of water stored behind these dams sums to 6.2 km3.
The red dots indicate the newly built dams and reservoirs each year, and the yellow dots represent the dams already in place.
The dams and reservoirs do not only store water, they also trap the incoming sediment that the river transports. Consequently, much less sand and clay travels to the coast, where it would normally be depositing in the delta region. The reduced sediment load of major rivers has influenced the vulnerability of many deltas worldwide.
Educational materials have been developed for this dataset, including a few PowerPoint slides, that can be used on a supplementary screen while viewing the dataset on Science On a Sphere®. Also, a discussion-based lesson plan can be used to facilitate student learning about the economics and ecology of dams.
Lehner, B., C. Reidy Liermann, C. Revenga, C. Vörösmart, B. Fekete, P. Crouzet, P. Döll, M. Endejan, K. Frenken, J. Magome, C. Nilsson, J.C. Robertson, R. Rodel, N. Sindorf, and D. Wisser. 2011. High-Resolution Mapping of the World's Reservoirs and Dams for Sustainable River-Flow Management. Frontiers in Ecology and the Environment 9:494-502. DOI: 10.1890/100125.
Japan built many dams already in the early 19th century.
In the U.S. East Coast, many medium-sized dams were constructed for grain milling and saw mills pretty early on.
In the 20th century, large engineering projects developed dams in more arid regions for drinking water and irrigation water storage and worldwide for electric power generation. The Hoover Dam, constructed in the 1930s on the border of Arizona and Nevada, is one example.
Most recently, large construction projects have been completed in China, including the Three Gorges Dam on the Yangtze River. The Three Gorges Dam is the world's largest hydroelectric facility.